JP2003120692A - Method of manufacturing metal ball retainer for bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a metal ball retainer for a bearing to manufacture the metal retainer with excellent lubricant retaining performance efficiently and easily at a low cost. SOLUTION: On this method of manufacturing the metal retainer for the bearing, a pair of waveform rings 2 alternately formed of recessed spherical parts 3 and flat parts 4 are made by press forming, and the metal ball retainer is manufactured by connecting and integrating the corresponding flat parts of a pair of the waveform rings 2 each other with the corresponding recessed spherical parts placed to face each other. For the press forming, minute recessed/projecting machined parts 25 are precedently formed on the outer peripheral surface of a metal mold element 20 for press-molding the recessed spherical part 3 by an electric discharge machining. When press-forming, minute recessed/ projecting parts 15 are formed on a recessed spherical surface of the recessed spherical parts 3 by transferring the minute recessed/projecting machined parts 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a metal ball cage for bearings, which is assembled to a rolling ball bearing that supports rotating parts of various mechanical devices.

[0002]

2. Description of the Related Art A rolling ball bearing holds a plurality of balls rollably between an inner ring and an outer ring, and holds a plurality of balls at equal intervals in the circumferential direction. As a container, a corrugated cage obtained by press-forming an annular metal plate is well known.

In this corrugated cage, a pair of corrugated rings, in which concave ball-holding portions and flat portions are alternately formed, are arranged so as to oppose each other. The plurality of balls are rotatably held at equal intervals in the circumferential direction by being inserted and attached and the flat portions being connected and integrated via rivets.

The ball retainer is installed between the inner ring and the outer ring in a state in which the ball is rotatably held, and the inner ring and the outer ring are supported rotatably relative to each other through the ball, thereby forming a bearing. It is what is done.

In such a ball bearing, after assembly,
By injecting a lubricant such as grease into the inner surface (concave spherical surface) of the concave sphere of the ball cage, the frictional resistance between the ball and surrounding contact parts such as the cage, inner ring and outer ring is reduced. Therefore, it is considered that a stable rotation state can be obtained.

[0006]

However, in the above-mentioned conventional metal corrugated ball cage, the concave spherical surface is formed as a smooth surface having a surface roughness (Rmax) of about 2 to 3 μm. In this case, the holding force of the lubricant is low, the amount of lubricant injected into the concave spherical surface progresses at an early stage, lubrication becomes insufficient, and problems such as uneven wear and baking may occur due to oil shortage. Have a

Accordingly, the applicant of the present application has developed a technique for forming a large number of oil reservoir recesses on the concave spherical surface in order to improve the lubricant retaining performance on the concave spherical surface in the above corrugated ball cage (practical use. New model registration No. 2503952).

The oil sump concave portion in this prior art has a bag shape or a dovetail groove cross-sectional shape whose inner side is wider than the opening, and the diameter of the opening is 0.1 to 0.1 mm.
The depth of the oil sump recess is set to about 1.0 mm, and is set to about 1/3 of the plate thickness of the recessed sphere. In other words, in the ball cage of the above-mentioned prior art, the size and depth of the oil sump concave portion are formed larger than the size such as the plate thickness and the size of the concave ball holding portion, so that the finishing press step, etc. During the press forming process, there are many product defects such as the occurrence of cracks at the oil sump recesses as crack starting points, which may reduce the production efficiency and increase the cost.

Further, as in the above-mentioned prior art, it takes a lot of time and complicated steps to form a large number of independent oil-storing recesses in the ball-holding recessed sphere, so that the number of working steps increases. As a result, the manufacturing becomes difficult and the cost may further increase.

The present invention has been made in view of the above circumstances, and provides a metal ball retainer excellent in lubricant retaining performance.
An object of the present invention is to provide a method for manufacturing a metal ball cage for bearings, which can be manufactured efficiently, at low cost, and easily.

[0011]

The inventor of the present invention found a peculiar structure capable of achieving the above object as a result of thorough experiments and researches on a metal ball cage, and made the present invention. I arrived.

That is, according to the present invention, a pair of corrugated rings in which concave ball portions for holding balls and flat portions are alternately formed are manufactured by press-forming a metal plate, and the pair of corrugated rings is A method for manufacturing a metal ball retainer in which corresponding flat portions are connected and integrated in a state where the corresponding concave spherical portions are arranged to face each other, wherein the concave spherical portions are pressed in a press forming process. A fine concavo-convex processed portion is previously formed on the outer peripheral surface of the die element for molding by electric discharge machining, and during press molding, the fine concavo-convex processed portion is transferred to the concave spherical surface of the concave spherical portion to form a fine concavity and convexity. The gist is to form the uneven portion.

In the method for manufacturing a metal ball cage for bearings according to the present invention, since fine concave and convex portions are formed on the concave spherical surface of the ball retaining concave spherical portion, the lubricant retaining performance on the concave spherical surface is improved. Can be improved.

Further, since a fine concavo-convex processed portion is formed in advance in the die element of the press molding die and the processed portion is transferred during the press molding process, the fine concavo-convex portion is formed on the concave spherical surface. The fine concavo-convex portion can be formed at the same time as the corrugating press molding, and it is not necessary to separately process the fine concavo-convex portion to prevent the number of working steps from increasing.

Since a fine concavo-convex portion is formed on the die element by using electric discharge machining which can be machined with higher precision, and the fine concavo-convex portion is transferred to form the fine concavo-convex portion, a concave spherical surface for holding a ball is formed. Can be finished with high dimensional accuracy without unevenness in degree, and the ball can be reliably held in a stable state with good positional accuracy.

On the other hand, in the present invention, it is preferable to adopt a structure in which a finished fine uneven portion is formed on the concave spherical surface of the concave spherical portion by subjecting the fine uneven portion to finish pressing.

That is, when this structure is adopted, the concave spherical surface for holding the ball can be finished with higher dimensional accuracy, and the ball can be held in a stable state with high positional accuracy and more reliably.

In the present invention, the surface roughness (Rmax) of the finished fine irregularities is set to 10 to 20 μm, or the surface roughness (Rmax) in the fine irregularities processed portion of the mold element is It is desirable to adopt a configuration in which Rmax) is set to 20 to 35 μm.

That is, when these structures are adopted, high dimensional accuracy can be obtained while sufficiently retaining the lubricant retaining performance on the concave spherical surface for retaining balls.

In the present invention, in the electric discharge machining, a voltage is applied between a metal work piece such as a die element and an electrode as a machining tool via an electric discharge machining liquid as an insulating medium. Then, spark discharge is performed, and the high temperature at that time finely melts and removes the surface layer of the workpiece.

Since this electric discharge machining is a thermal machining,
Unlike mechanical processing such as shot blasting and barrel processing, even high hardness metal materials that are difficult to cut can be processed with high precision, precision processing, curved surface processing,
Sphere processing and the like can be performed with high precision.

In electrical discharge machining, the roughness of the electrical discharge machined surface can be freely adjusted by appropriately changing the gap between the workpiece and the electrode (electrical discharge gap), and the degree of unevenness can be varied. It is possible to obtain a satin-finished processed surface with a small amount.

[0023]

1 to 5 are views showing a metal corrugated ball cage (1) manufactured by a manufacturing method according to an embodiment of the present invention. As shown in these figures, the ball retainer (1) includes a pair of corrugated rings (2) having the same shape and the same size. Corrugated ring (2)
Is obtained by a series of press-molding processes described in detail below, and concave ball portions (3) and flat portions (4) for holding balls are formed alternately in a constant pitch along the circumferential direction. ing. Further, as described later in detail, a satin-finished finished fine concavo-convex portion (15) is formed on the inner peripheral surface (concave spherical surface) of the concave spherical portion (3).

The corrugated rings (2) oppose the concave spherical surfaces of the ball retaining concave spheres (3), and the balls (5) as the rolling elements of the bearing are provided between the opposed portions. The ball cage (1) with balls can be arranged by stacking and stacking them, and by connecting the corresponding flat parts (4) with each other by joining them with rivets (6). It is composed.

To manufacture the ball cage (1) of this embodiment, first, a blank is punched out to punch a metal plate to obtain a ring product.

As the metal plate, a cold rolled steel plate such as SPCC or a hot rolled steel plate such as SPHC is preferably used.

Next, the ring product is press-formed into a substantially corrugated product by a wave-roughing roughing process to obtain a substantially corrugated product.

Next, in the first finishing pressing step, the above-mentioned substantially corrugated ring product is subjected to press forming to obtain a corrugated ring product. This corrugated ring product has substantially the same structure as the corrugated ring (2) that constitutes the ball retainer (1), and the ball retaining concave sphere portion (3) and the flat portion (4) are constant in the circumferential direction. They are formed in an alternating arrangement with a pitch.

In the present embodiment, in the press-molding die used in the first finishing pressing step, the die element (20) for molding the ball holding concave sphere portion (3) is unique to the present embodiment. What is used.

As shown in FIG. 6, this mold element (20)
Is a hemispherical surface (2) corresponding to the concave spherical shape of the concave sphere (3).
1) and a rod (22), one end of which is connected to the hemispherical surface portion (21).

Here, in this embodiment, the mold element (2
On the outer peripheral surface of the hemispherical surface part (21) in 0), a fine textured processed part (25) having a satin finish is formed by electric discharge machining.

In this electric discharge machining, the hemispherical surface (2
Electrode (30) made of copper or the like having an inner spherical surface (semi-concave spherical surface) processed surface (31) having a predetermined curvature corresponding to the outer peripheral surface of 1)
Is prepared. Then, in a liquid such as electric discharge machining oil as an insulating medium, the hemispherical surface portion (21) of the die element (20).
And the processed surface (31) of the electrode (30) are arranged relative to each other, the mold element (20) side is connected to the ground, the electrode (30) side is connected to a power source, and a voltage is applied between them. . As a result, arc discharge (A) is generated between the hemispherical surface portion (21) and the electrode (30), and due to the high temperature at that time, the outer surface portion of the hemispherical surface portion (21) is finely melted and removed. The fine concavo-convex processed portion (2
5) to form a matte surface.

In the present embodiment, in the first finishing pressing step, the fine concavo-convex processed portion (25) of the die element (20) by electric discharge machining is transferred to the concave spherical surface of the concave spherical portion (3) in the corrugated ring product. Thus, the fine concavo-convex portion (fine concavo-convex portion 15 before finishing) is formed on the concave spherical surface.

Here, the surface roughness of the fine concavo-convex portion (15) before finishing is made to be coarse (larger) in consideration of the reduction amount in the second finishing pressing step which will be performed later.

Specifically, the surface roughness (Rmax) of the hemispherical surface portion (21) of the die element (20) by electric discharge machining is
By adjusting the lower limit value to 20 to 35 μm, preferably the lower limit value to 25 μm or more and the upper limit value to 30 μm or less, the surface roughness of the fine uneven portion (15) before finishing obtained by transferring the rough surface is adjusted to the same degree.

The surface roughness of the fine concavo-convex processed portion (25) of the die element (20) is determined by the electrode (3
It can be adjusted by appropriately changing the discharge gap between the mold element (20) and the mold element (20). For example, when the discharge gap is increased, the surface roughness increases.

Next, in the second finish pressing step, finish molding is performed on the concave spherical surface of the ball holding concave sphere portion (3) in the corrugated ring product.

In the press-molding die used in the second finishing pressing step, as a die element for concave spherical surface finishing, those conventionally used, that is, a hemispherical surface portion having a smooth outer peripheral surface and the hemispherical surface portion thereof. A rod having one end connected to the rod is used.

As a result, in this second finishing pushing step,
Delicate dimensional adjustments such as the curvature and gaps of the concave spherical surface in the corrugated ring product are precisely performed, and at the same time, the fine unevenness before finishing transferred to the concave spherical surface is pressed and the tip of the convex portion is crushed. It is finished to be substantially smooth to form a finished fine uneven portion (15).

The degree of unevenness of the fine unevenness portion (15) immediately after the first finishing pressing step (before finishing) is shown in the graph of FIG. 7, and the unevenness degree of the fine unevenness portion (15) after the second finishing pressing step is shown. This is shown in the graph of FIG. As shown in both graphs, in the present embodiment, before-finishing fine irregularities (1
In 5), the convex portion that largely protrudes to the surface side (contact surface side with the ball) is crushed in the finished fine unevenness portion (15), so that the surface side is finished to be substantially smoother than the inner side. Has been.

Here, in the present embodiment, the surface roughness (Rmax) of the finished fine irregularities (15) is 10 to 20 μm.
m, preferably 15 μm or more. That is, when the surface roughness is too small, it is not possible to sufficiently secure the retaining force of the lubricant on the ball retaining concave spherical surface in the ball retainer (1) to be manufactured, and the lubricant decreases early. Then, the frictional resistance increases and the bearing performance may deteriorate, which is not preferable. On the other hand, if the surface roughness is too large, the degree of unevenness on the ball holding concave spherical surface in the manufactured ball cage (1) varies, the sliding resistance with the ball increases, and the rotational torque increases. Is increased and the bearing performance may be deteriorated, which is not preferable.

Further, in the present embodiment, since the final finishing of the concave sphere portion (3) is performed by the second finishing pushing step, in consideration of the dimensional reduction due to the second finishing pushing step, the above-mentioned first finishing pushing step is carried out. 1 The finishing push step and the like are performed.

On the other hand, after performing the second finishing pressing step,
A rivet hole (4) is punched out in the area of the flat portion (4) between the concave spheres (3) by a rivet hole forming step.
a) is formed.

Then, a barrel treatment step is carried out to remove burrs remaining in the ring product at the time of punching to obtain a corrugated ring (2).

Thereafter, in the rivet inserting step, the corrugated rings (2) are made into a set of two pieces and are connected by the rivets (6) via the balls (5) as described above. The metal corrugated ball cage (1) is formed and then assembled to the bearing.

In the ball bearing thus obtained, since the concave-convex spherical surface (15) for holding the ball of the cage (1) is formed with fine irregularities (15), the holding force of the lubricant on the concave spherical surface increases, The lubricant is continuously supplied around the ball (5). For this reason, it is possible to prevent problems such as uneven wear and baking due to oil shortage, to maintain a stable rotating state for a long time, and to obtain high quality and performance.

Further, in the ball cage (1) of this embodiment, a fine concavo-convex processed portion (25) is previously formed on the die element (20) by electric discharge machining, and the processed portion (2) is formed.
Since 5) is transferred at the time of press molding (during the first finish pressing), the fine concavo-convex portion (15) is formed on the concave spherical surface. Therefore, it is separately processed for forming the fine concavo-convex portion (15). Since it is not necessary, it is possible to prevent the number of working steps from increasing. Therefore, the manufacturing can be easily performed, the production efficiency can be improved, and the cost can be reduced.

Further, in this embodiment, the cage (1)
Compared with the plate thickness and size of No. 3, since it is only to form an extremely fine uneven portion (15), it is possible to reliably prevent the uneven portion (15) from becoming a crack starting point during pressing. Further, it is possible to effectively prevent the occurrence of product defects, and further improve the production efficiency.

Moreover, in this embodiment, the corrugated ring (2) constituting the cage (1) is removed by the blank removing step,
Since it is manufactured only by press forming processes such as wave roughing finishing process, first finishing pressing process, second finishing pressing process, and rivet drilling process, heterogeneous machining such as cutting may be involved. Since it does not exist, it is possible to smoothly perform the transition between the respective steps, and in this respect as well, the production efficiency can be further improved.

Further, in the present embodiment, a fine concavo-convex portion (25) is formed on the die element (20) by using electric discharge machining capable of high-precision machining, and is transferred to the fine concavo-convex portion ( In addition to forming 15), the fine concavo-convex portion (15) is subjected to finishing processing (second finishing pressing processing), so that the ball holding concave spherical surface is finished with high dimensional accuracy without unevenness in degree. Therefore, the ball (5) can be surely held in a stable state with high positional accuracy, and the quality of the ball retainer (1) and eventually the bearing product can be further improved.

Further, the transferred fine concave-convex portion (15) is subjected to finish pressing to crush the tip of the convex portion smoothly, so that the ball (5) is scratched by contact with the tip of the convex portion. It is possible to surely prevent the trouble of.

In the above embodiment, the fine concavo-convex processed portion (25) is formed on almost the entire outer circumference of the hemispherical portion (21) of the mold element (20) to hold the ball in the ball cage (1). Fine concavo-convex portion (15) over almost the entire area of the concave spherical surface.
However, the present invention is not limited to this, and the fine concavo-convex portion may be partially formed only in a required region of the concave spherical surface. For example, the semi-spherical portion (21) of the die element (20) is partially subjected to electric discharge machining to partially form fine irregularities in a region corresponding to a so-called equator peripheral region where the rotational peripheral velocity of the ball is high. It may be done.

[0053]

As described above, according to the method of manufacturing the metal ball cage for bearings of the present invention, the outer peripheral surface of the die element for press-molding the concave ball-holding portion is formed by electric discharge machining. , The fine concavo-convex processed portion is formed in advance, and at the time of press molding, the fine concavo-convex portion is formed by transferring the fine concavo-convex processed portion on the concave spherical surface of the concave spherical portion,
The holding power of the lubricant on the concave spherical surface increases and the lubricant is supplied around the ball without interruption, so it is possible to prevent problems such as uneven wear and baking due to oil shortage, and a stable rotation state. Can be maintained for a long time, and high quality and performance can be obtained. Furthermore, since a fine concavo-convex processed portion is formed in advance on the die element, and the processed portion is transferred at the time of press molding for forming the concave spherical portion, so that the fine concavo-convex portion is formed on the concave spherical surface.
Since it is not necessary to separately process for forming the fine concavo-convex portion, it is possible to prevent an increase in the number of working steps, facilitate manufacturing, improve production efficiency, and reduce cost. In addition, since a fine concavo-convex portion is formed on the die element by using electric discharge machining that can perform high-precision machining, and the fine concavo-convex portion is transferred to form a fine concavo-convex portion, the concave spherical surface for ball holding has a high dimension. There is an effect that the ball can be finished with high accuracy, the ball can be reliably held in a stable state with high positional accuracy, and the quality can be further improved.

In the present invention, when finishing processing is performed on the fine irregularities of the concave spherical surface for holding a ball, the concave spherical surface for holding a ball can be finished with higher dimensional accuracy, and the ball can be stably positioned with high accuracy. In addition, there is an advantage that it can be held more reliably and the quality can be further improved.

In the present invention, when the surface roughness in the finished fine concavo-convex portion or the surface roughness in the fine concavo-convex processed portion of the die element is set within a specific range, the above effect can be obtained more reliably. The advantage is that

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a metal ball holder for bearings manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a plan view showing a ball cage according to the embodiment.

FIG. 3 is a side sectional view showing the ball cage of the embodiment.

FIG. 4 is a plan view showing a part of a corrugated ring applied to the ball cage according to the embodiment.

FIG. 5 is an enlarged perspective view showing the periphery of the spherical portion in the corrugated ring of the embodiment.

FIG. 6 is a perspective view showing a die element used in the manufacturing method of the embodiment in a state in which electric discharge machining is being performed.

FIG. 7 is a graph showing the degree of concavity and convexity of the fine concavo-convex portion on the concave spherical surface for holding balls immediately after the first finishing pressing step in the manufacturing method of the embodiment.

FIG. 8 is a graph showing the degree of unevenness of the fine unevenness on the ball-holding concave spherical surface after the second finishing pressing step in the manufacturing method of the embodiment.

[Explanation of symbols]

1 ... Ball cage 2 ... Wave ring 3 ... concave sphere 4 ... Flat part 5 ... ball 15 ... Fine irregularities 20 ... Mold element 25 ... Fine irregularity processing part

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16C 33/66 F16C 33/66 Z (72) Inventor Asaichi Tateiwa 3-3-5 Tenmabashi, Kita-ku, Osaka City Nakanishi Kinzoku Kogyo Co., Ltd. F term (reference) 3C059 AA01 AB01 HA04 3J101 AA02 AA32 AA42 AA62 BA37 BA45 BA47 CA14 DA09 EA02 EA63 FA32 FA44 4E050 JB06 JD03

Claims (4)

[Claims] 1. A pair of corrugated rings in which concave ball portions for holding balls and flat portions are alternately formed by press-forming a metal plate, and the pair of corrugated rings correspond to each other. A method for manufacturing a metal ball retainer, in which concave flat portions are arranged so as to face each other, and corresponding flat portions are connected and integrated with each other, in order to press-mold the concave spherical portions in a press molding process. A fine concavo-convex portion is formed in advance on the outer peripheral surface of the die element by electrical discharge machining, and during press molding, the fine concavo-convex portion is transferred to the concave spherical surface of the concave spherical portion by transferring the fine concavo-convex portion. A method of manufacturing a metal ball cage for bearings, which is characterized in that it is formed. 2. The metal ball retainer for a bearing according to claim 1, wherein the finished fine irregularities are formed on the concave spherical surface of the concave sphere by subjecting the fine irregularities to finish pressing. Production method. 3. The surface roughness (Rmax) of the finished fine irregularities is set to 10 to 20 μm.
A method for manufacturing the metal ball cage for bearings according to claim 1. 4. The production of a metal ball cage for bearings according to claim 1, wherein the surface roughness (Rmax) in the finely textured portion of the die element is set to 20 to 35 μm. Method.