JP3084540B2 - Bearing for swivel seat and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing for a swivel seat used for a construction machine or a large-sized machine and a method for manufacturing the same.

[0002]

2. Description of the Related Art A swivel bearing, commonly known as a turntable bearing, is a single bearing that is designed to receive an axial load, a moment load, and a radial load. Also, a fixing mounting hole is provided on the raceway itself. Depending on the application, there are bearings that support a large load and bearings that require precision and rigidity.

[0003] When the race of the bearing for a swivel bearing is of a large diameter, it is used for structural carbon steel or structural alloy steel (SCM440, SCM440).
CM445, etc.) is used, and the rolling surface is induction hardened.
A hardened layer is provided by tempering to provide abrasion resistance.

In the induction hardening, a single high-frequency coil is heated by a single high-frequency induction by making a single high-frequency coil uniformly close to the entire circumference of the rolling surface. Although it is desirable, on the other hand, a dedicated high-frequency coil must be prepared every time the size and shape of the bearing ring changes, and a high output is required for the high-frequency oscillator. Therefore, in the case of large-diameter races, the small coil is brought close to the raceway, induction heating is usually performed with the raceway rotating at a constant speed, and the induction heating part on the raceway continuously moves. A method of cooling water immediately after passing through the coil is adopted.

[0005] In this moving quenching, if the already quenched portion on the rolling surface is heated and quenched again and the quenched portion overlaps, quenching cracks occur in the overlapped portion or a soft portion due to reheating causes wear resistance. Decrease. So, conventionally,
The unrolled portion was left soft between the quenching start and end portions on the rolling surface.

As shown in FIG. 4, a single row ball bearing in which the rolling surfaces 12, 22 of the outer ring 1 and the inner ring 2 are both semicircular in cross section is used as the rotating seat bearing, as well as the axial load and the radial load. It is widely used because of its simple structure. In this type of ball bearing, the inner ring 2 or the outer ring 1 is provided with a through-hole that opens on the peripheral surface including the rolling surface,
At the time of assembling the bearing, the inner ring 2 and the outer ring 1 are arranged, the balls 3 are inserted from the through holes into the rolling grooves formed with the rolling surfaces 12 and 22 facing each other, and the through holes are plugged. Was.

The plug is provided with a concave curved surface having the same shape as the rolling surface on one end face, and a steel stopper body provided with a pin hole on the other end side is inserted into the through hole, and the side face of the bearing ring is formed. Further, a taper pin was fitted into the stop hole to prevent the stopper from coming off and rotating.

[0008]

The unquenched soft part accompanying the moving and quenching of the raceway raceway surface has low wear resistance, so that the load area on the raceway surface is limited as a bearing for a turning seat. In bearing applications in which the load extends over the entire circumference of the rolling surface, the bearing is likely to be worn during use.

In addition, when the through hole is plugged after the ball rolling element is inserted, the plug requires machining for fixing the plug with a tapered pin, so that the rolling end formed by the plug end face is required. The surface remained soft and had the same disadvantages of wear resistance as described above.

[0010] The present invention eliminates the soft rolling surface unique to a large diameter bearing for a swivel bearing caused by quenching by high-frequency transfer heating, makes the rolling surface a uniform hardened hardened surface, and improves wear resistance. An object of the present invention is to provide a bearing for a turning seat having excellent turning accuracy and a manufacturing method thereof.

[0011]

A bearing for a swivel bearing according to the present invention is a bearing for a swivel seat having a surface hardened layer by moving quenching of high-frequency heating on a rolling surface of a bearing ring. A tap hole drilled in the radial direction of the bearing ring with an opening formed by cutting the contact surface on the peripheral surface having a contact surface, and the surface hardening using the opening of the tap hole as the start and end of moving quenching. Layer, a plug body having a concave curved surface hardened and hardened on one end surface, and a plug inserted and fixed in the plug hole.The rolling surface is formed with the concave curved surface, and the rolling surface is uniform over the entire circumference of the rolling surface. It is characterized by having a surface hardened layer.

[0012] The bearing for a swivel seat is particularly provided with a rolling groove formed by piercing the plug hole in the radial direction of the raceway through the raceway, and forming an inner raceway surface and an outer raceway surface opposite to each other. A hole having a through hole for charging a ball is used.

[0013] Further, in the manufacturing method, a step of forming a rolling surface on the bearing ring, and a plug in a radial direction of the bearing ring such that an opening having a diameter larger than the width of the rolling surface cuts the rolling surface. A step of drilling a hole, a moving quenching step of continuously moving a heating unit using a high-frequency coil to the rolling surface with the opening as a starting end, and a moving quenching step with the opening as an end. A step of forming a hardened layer by forming a curved surface, and a step of inserting and fixing the plug into the perforation;
The concave curved surface is used as a rolling surface, and a uniform hardened surface layer is provided over the entire circumference of the rolling surface.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of a bearing for a swivel seat according to the present invention.

The bearing for the swivel seat is a single-row ball bearing shown in FIG. 4 and has a gear 25 provided inside the inner ring 2, and is made of structural carbon steel, for example, S55C material, or The inner race 2 and the outer race 1 are formed by forging into a ring shape from a low alloy steel for use, for example, SCM440 or SCM445.

FIG. 1 is a partial perspective view of the inner peripheral surface 11 of the outer ring 1. The inner peripheral surface 11 of the outer ring 1 is turned with a rolling surface 12 having a substantially semicircular shape in a vertical section of the outer ring. Formed, also
A through hole 4 having a circular opening 40 having a diameter larger than the width of the rolling surface 12 is provided from the inner peripheral surface 11 to the outer peripheral surface 15 so as to penetrate the outer ring 1 main body. 12 is cut.

In the quenching process of the rolling surface 12 of the inner peripheral surface 11, a small high-frequency coil (not shown) and a water injection pipe (not shown) are brought close to the inner peripheral surface 11, and the outer ring 1 is rotated by a rotating device ( Induction hardening is performed over the entire circumference of the rolling surface 12 by high-frequency induction heating and water injection immediately after heating while rotating (not shown).

In this induction hardening, the starting end of the quenching heating of the rolling surface 12 is set to the outer edge 9 of the opening 40 of the through hole 4.
1, the high-frequency induction heating portion is formed by
The upper end is circulated, and the end of the quenching heating is set to the other outer edge 92 of the opening 40 of the through hole 4.

As described above, the start end 91 and the end end 92 of the high-frequency heating are connected to the peripheral edge 9 of the opening 40 of the through hole 4 penetrating the outer race 1.
Since it is 1,92, there is no portion where the starting end and the end of the high-frequency heating overlap on the rolling surface 12, and no unquenched portion is formed between the starting end and the end. Remaining rolling surface 12
Is a uniform hardened and hardened surface 9.

After induction hardening, tempering is performed,
Enhanced toughness to release a portion of the quenching residual stress was adjusted to about Rockwell C hardness H _RC 55 to 60, the rolling is performed precision polishing of contact surface 12.

The inner race 2 also has a rolling surface 2 on the outer peripheral surface 21.
2 is subjected to the same induction hardening, but the inner ring is provided with a gear 25 on the inner periphery, so the hole opened in the rolling surface 22 is not a through hole, but a closed hole closed inside the inner ring body. Is different.

FIG. 2A is a partial sectional view of the inner ring in which the closing hole 41 formed in the outer peripheral surface 21 of the inner ring 2 is plugged.
The plug 5 for plugging is formed of structural carbon steel S55C or structural alloy steel SCM440, or the like, and has an outer diameter whose outer periphery fits into the inner periphery of the closing hole 41 as shown in FIG. A semi-cylindrical concave curved surface 52 having the same cross section as the rolling surface 22 of the inner ring 21 is formed at one end, and a tapered pin hole 61 is provided at the other end. The concave curved surface 52 is provided with a hardened layer 9 formed by induction hardening. Hardened layer 9 performs tempered after induction hardening, is prepared on the rolling surface hardness and surface hardness of the comparable H _RC 55 to 60 of the contact surface.
When the plug 5 is inserted into the closing hole 41 of the inner ring 2 and the tapered pin 6 is inserted into the pin holes 61 from the side surface of the inner ring 2 and the plug 5 is fixed, the concave curved surface of the plug 5 is formed. 52 forms a continuous surface with the rolling surface 22 of the outer peripheral surface 21 and becomes a rolling surface 22 ′ that supports the load of the ball 3.

FIG. 3 shows the through hole 4 of the outer race 1 shown in FIG.
1 shows a cross-sectional view of a bearing plugged and assembled. The through holes 4 of the outer race 1 are used as holes for charging the balls 3 and the rolling grooves 12 and 22 of the flexible spacer (retainer) (not shown) at the time of bearing assembly. Thereafter, in the same manner as in FIG. 2, the plug 5 is inserted through the opening on the outer peripheral surface side of the through hole 4, fixed to the outer ring 1 by the tapered pin 6, and the quenched and hardened semicircle of the plug 5 is inserted. The concave concave surface 52 is used as the hardened rolling surface 12 '.

In this embodiment, an internal gear type bearing for a swivel seat is exemplified. However, the present invention is similarly applied to an external gear type bearing. In this case, a ball insertion hole is provided in an inner ring having no gear. Can be

With respect to the quenching treatment of the plug 5,
Although the method in which the concave curved surface 52 is induction hardened is shown, as the other method, a method in which the entire plug body 5 is integrally quenched (soak quenching) or a method in which only the concave curved surface 52 after the entire heating is poured with water is appropriately employed. Is done.

In the present embodiment, after the through-hole / closure hole 4 is provided on the raceway peripheral surface including the rolling surfaces 12 and 22, the start and end of the induction hardening are determined with the hole as a starting point. The present invention is not limited to the example, and after high-frequency moving heat quenching is performed first, a through-hole may be provided for cutting and opening a small unquenched portion between the start end and the end.

[0027]

According to the swivel bearing of the present invention, while the induction hardening method is moving hardening in the solid direction of the rolling surface, the rolling surface is provided with a uniform surface hardened layer over the entire circumference. Since it has excellent wear properties, it can be widely used in applications where the entire rolling surface is a high-load surface, and is useful for improving turning accuracy.

Further, at the time of induction hardening, a heating method using a large-diameter high-frequency coil is not necessary, and various kinds of various large-diameter bearings can be hardened by a small-output high-frequency oscillator and a small-diameter high-frequency coil. It is effective for general use and reduction of manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an inner peripheral surface side of an outer race of a bearing for a turning seat.

FIG. 2 is a sectional view (A) of a plug stopper portion of the inner ring of the internal gear type bearing;
Sectional view (B) and front view (C) of the plug.

FIGS. 3A and 3B are a cross-sectional view of a bearing for a swivel seat having a plug plug portion on an outer ring, a cross-sectional view of the plug, and a front view of the same.

FIG. 4 is a partial sectional view of a ball bearing for a swivel seat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer ring 12 Outer ring rolling surface 2 Inner ring 22 Inner ring rolling surface 3 Ball 4 Plug hole 5 Plug body 6 Taper pin 9 Hardened hardened layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 19/16 F16C 33/62

Claims (4)

(57) [Claims] 1. A bearing for a swivel seat having a surface hardened layer formed by moving and quenching by high-frequency heating on a raceway surface of a raceway, wherein the raceway ring has an opening formed by cutting the raceway surface into a peripheral surface having the raceway surface. A tap hole having a portion, drilled in the radial direction of the bearing ring, the surface hardened layer having the opening of the tap hole as a start end and an end of moving quenching, and a concave curved surface hardened and hardened on one end surface. And a plug fixedly fitted in the plug hole, and the concave curved surface is used as a rolling surface, and a hardened surface layer is provided over the entire circumference of the rolling surface. 2. The swivel seat according to claim 1, wherein the plug hole is a charging hole for charging a ball into a rolling groove formed between the inner ring rolling surface and the outer ring rolling surface. bearing. 3. A method for manufacturing a bearing for a swivel seat having a surface hardened layer formed by moving and quenching by high-frequency heating on a rolling surface of a bearing ring, wherein: a step of forming a rolling surface on the bearing ring; A step of piercing a tap hole in the radial direction of the raceway so that an opening having a diameter larger than the width cuts the rolling surface, and then continuously moving a heating unit using a high-frequency coil to the rolling surface with the opening as a starting end. Moving quenching step with the opening as the end,
A step of forming a quenched and hardened layer by separately forming a concave curved surface on one end surface of the plug, and a step of inserting and fixing the plug in the perforation, and a rolling surface with the concave curved surface A method for manufacturing a bearing for a swivel seat, comprising a hardened surface layer over the entire circumference of the rolling surface. 4. A hole is bored through the raceway in a radial direction of the raceway ring, and a ball is inserted into a raceway groove formed between the raceway surface of the inner race and the raceway surface of the raceway. 4. The method for producing a bearing for a swivel seat according to claim 3, wherein the through hole is a charging hole.