JP2709556B2 - Induction quenching method for thin ring-shaped workpiece - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for induction hardening a thin ring-shaped workpiece.

[0002]

2. Description of the Related Art In a conventional induction hardening method for a thin ring-shaped work (for example, a thin outer ring of a ball bearing), as shown in a time chart of FIG. After the inner peripheral surface is heated by an annular high-frequency heating coil for the inner peripheral surface (hereinafter, the high-frequency heating coil is also simply referred to as a heating coil), a cooling liquid is injected to the inner peripheral surface to quench the inner peripheral surface. During the heating and cooling of the inner peripheral surface, the cooling liquid is continuously jetted to the outer peripheral surface from the annular coolant jetting jacket arranged to face the outer peripheral surface of the work.

At the same time as the quenching of the inner peripheral surface is completed, the injection of the coolant to the outer peripheral surface is stopped. Next, the jacket for cooling liquid injection is removed, and an annular heating coil for the outer peripheral surface is disposed so as to face the outer peripheral surface of the work. Then, the outer peripheral surface is heated by the heating coil. The outer peripheral surface is cooled by injecting a cooling liquid to the surface to complete the quenching of the outer peripheral surface.

When quenching a plurality of workpieces, first,
After quenching the inner surface of all the workpieces, remove the jacket, install a heating coil on the outer surface instead, and then quench the outer surface of all the workpieces. Finish the surface quenching.

As an example of the duration of each stage of the above-mentioned quenching operation, as shown in FIG. 6, the inner peripheral surface is heated for 4 seconds, the inner peripheral surface is cooled for 4 seconds, the outer peripheral surface is heated for 2 seconds, and the outer peripheral surface is cooled. 2 seconds and the start of the outer peripheral surface heating is set to 0.5 seconds after the inner peripheral surface quenching is completed, the time required for quenching one workpiece is 12.5 seconds. The time to remove and attach the outer peripheral surface heating coil is added. The reason why the inner peripheral surface is heated longer than the outer peripheral surface is as follows.

That is, since the outer peripheral surface of the work is inside the annular outer peripheral surface heating coil disposed outside the outer peripheral surface so as to be opposed to the outer peripheral surface, the magnetic flux generated by the heating coil can effectively reduce the outer peripheral surface. Crosses the surface. However, since the inner peripheral surface of the work is located outside the annular inner peripheral surface heating coil disposed inside the inner peripheral surface so as to face the inner peripheral surface, even if the inner peripheral surface heating coil is made of a magnetic material, Even when the core is mounted, the magnetic flux crossing the inner peripheral surface is not as large as the outer peripheral surface. Therefore, the heating time of the inner peripheral surface is longer than the heating time of the outer peripheral surface.

[0007] Since the inner peripheral surface is heated for a long time and the inner peripheral surface is thin in this way, the heat effect at the time of heating the inner peripheral surface extends to the outer peripheral surface, which may cause soaking. Therefore, the outer peripheral surface is cooled while the inner peripheral surface is being heated.

[0008]

[Problems to be Solved by the Invention] However, recent competition between companies is fierce, and there is an increasing demand for shortening the quenching time. In addition, in the induction hardening of such a thin ring-shaped workpiece, it is necessary to further shorten the quenching time. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an induction hardening method for a thin-walled ring-shaped work capable of shortening the hardening time.

[0009]

According to a first aspect of the present invention, there is provided a method for induction hardening of a thin ring-shaped workpiece having an outer peripheral surface and an inner peripheral surface, wherein the induction hardening method is disposed so as to face the inner peripheral surface. It said by the annular inner peripheral surface hardening coil
A first step of heating the peripheral surface , and after the first step, the inner peripheral surface
And a second step of cooling the outer peripheral surface.
Heating of the outer peripheral surface by the provided annular outer surface quenching coil
Starts simultaneously with the start of the first step, and ends in the middle of the first step.
The third step to be completed, and after the third step, the second step is almost completed.
Quenching liquid from the outer surface quenching coil
And a fourth step of cooling the outer peripheral surface by irradiation .

According to a second aspect of the present invention, in the induction hardening method for a thin ring-shaped workpiece having an outer peripheral surface and an inner peripheral surface, an annular inner peripheral surface is provided so as to face the inner peripheral surface. A first step of heating the inner peripheral surface by a quenching coil, a second step of cooling the inner peripheral surface after the first step, and an annular outer peripheral surface arranged to face the outer peripheral surface. Heating of the outer peripheral surface by the input coil starts the first step
A quenching liquid is injected from the outer peripheral surface quenching coil to the outer peripheral surface until the third step , which starts before the first step and ends in the middle of the first step, and after the third step, until almost the second step is completed. And a fourth step of cooling the outer peripheral surface.

[0011]

【Example】 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
I do.

FIGS. 1 and 2 illustrate the implementation of the method of the present invention.
For explaining one embodiment of an induction hardening device capable of forming
FIG. 1 is a vertical sectional front view, and FIG. 2 is an electric circuit diagram.
It is. FIG. 3 shows a work by the induction hardening apparatus shown in FIG.
4 and 5 are time charts showing an example of the quenching method.
In the time chart of the quenching method according to claims 1 and 2, respectively.
is there.

The induction hardening apparatus of this embodiment is an apparatus for hardening the outer peripheral surface and the inner peripheral surface of a thin ring-shaped work such as a thin outer ring of a ball bearing. As shown in FIG. 1, the workpiece 100 has an outer peripheral surface 101 having a straight cross section and an inner peripheral surface 103 having an arc-shaped recess in the cross section.
Then, a hardened layer 102 is formed on the inner peripheral surface 103, and a hardened layer 104 is formed on the inner peripheral surface 103.

As shown in FIGS. 1 and 2, the induction hardening device is disposed outside the outer peripheral surface 101 of the work 100 so as to face the outer peripheral surface 101 and sprays a cooling liquid onto the outer peripheral surface 101. Annular outer surface quenching coil 10 which also serves as
And the inner peripheral surface 10 so as to face the inner peripheral surface 103 of the workpiece 100.
3 is attached to the inner peripheral surface hardening coil 20 so as to cover the annular inner peripheral surface hardening coil 20 and the surface of the inner peripheral surface hardening coil 20 that is not opposed to the workpiece 100. An annular core 31 made of a magnetic material such as ferrite, an inner peripheral surface coolant supply pipe 30 having an opening at a substantially central portion of the annular core 31, and fixed to the upper end of a vertical work support rotation shaft 40, and horizontally The work includes a lower concentrating ring 41 also serving as a support member for a lower periphery of the arranged work 100, and an annular upper concentrating ring 42 placed on the upper periphery of the work 100. The concentring serves to make the quenching depth in the direction perpendicular to the circumferential direction of the workpiece 100 substantially constant.

The outer peripheral surface quenching coil 10 having a rectangular cross section has a hollow portion 12 on the outer peripheral surface 101 of the work 100 through which the cooling liquid L for quenching flows, and communicates with the hollow portion 12. A coupler to which a plurality of coolant injection holes 11 opened on a surface facing the surface 101 and a coolant supply pipe (not shown) are connected.
13 and. Inner peripheral surface hardening coil 20 with circular cross section
Is provided with a hollow portion 21 having a circular cross section through which the coolant of the coil 20 flows.

An inner peripheral surface coolant supply pipe disposed substantially vertically.
Between the lower end of 30 and the core 31, an inner peripheral coolant supply pipe
The cooling liquid R ejected from the inner peripheral surface cooling liquid supply pipe 30 while supporting the space 30 and closing the space between the cooling liquid supply pipe 30 and the core 31 An annular inner peripheral surface coolant supply pipe holding member 32 is provided to prevent overflow from above the space.

Next, an electric circuit of the induction hardening apparatus will be described. As shown in FIG. 2, the cutting point of the outer surface hardening coil 10 is connected to a transformer 55 whose input side is connected to a high frequency power supply 56 via a pair of power supply conductors 19, 19 and a pair of switches 51, 51.
Is connected to the output side. The inner surface hardening coil 20
Is a pair of feed conductors 29, 29 and a pair of switches 53,
Also connected to the output side of a transformer 55 via 53. 52 and 54 are cylinders for turning on and off the switches 51 and 53, respectively.

Hereinafter, a work 1 by this induction hardening device will be described.
An example of the quenching method 00 (hereinafter referred to as a first method) will be described with reference to FIG. The outer peripheral surface hardening coil 10 and the inner peripheral surface hardening coil 20 are fixed at the positions shown in FIG. Prior to the start of the quenching operation, the lower outlet ring 41 and the work supporting rotary shaft 40 are lowered from the position shown in FIG. Work 1 to be hardened
After placing the work 100 on the lower outlet ring 41, the upper outlet ring 42 is attached, the work supporting rotary shaft 40 is raised in the direction of arrow P, and the work 100 is coiled on the outer peripheral surface and the inner peripheral surface. 20.

Next, the work supporting rotary shaft is moved, for example, by the arrow Q.
When the switch 51 is turned on by operating the cylinder 52 while rotating in the direction of, the high-frequency current generated from the high-frequency power supply 56 flows through the transformer 56 and the switch 51 to the outer peripheral surface hardening coil 10 and The outer peripheral surface 101 is heated.
When the outer peripheral surface 101 is heated for a predetermined time, the switch 52 is turned off by operating the cylinder 52. Next, when the cooling liquid L is supplied to the hollow portion 12 of the outer peripheral surface quenching coil 10, the cooling liquid L is injected from the cooling liquid injection hole 11 to the outer peripheral surface 101, and
Is cooled.

At this time, when the heating of the outer peripheral surface 101 is completed, the cylinder 54 is operated and the switch 53 is turned on. A high-frequency current is applied to the inner peripheral surface hardening coil 20 to heat the inner peripheral surface 103 of the workpiece 100. After heating the inner peripheral surface 103 for a predetermined time,
After operating the cylinder 54 to turn off the switch 53,
When the coolant R is supplied to the inner peripheral coolant supply pipe 30, the coolant R is supplied to the inner peripheral coolant supply pipe 30 and the lower outlet ring 41.
After passing between the inner peripheral surface hardening coil 20 and the inner peripheral surface 103 of the workpiece 100 to cool the inner peripheral surface 103,
It flows out over the upper outlet ring 42. While the inner peripheral surface 103 is being heated and cooled, the injection of the cooling liquid L from the outer peripheral surface quenching coil 10 is continued. And the inner surface
When the quenching of 103 is completed, the rotation of the workpiece 100 is stopped.

As an example of the duration of each stage of the quenching operation, as shown in FIG. 3, the outer peripheral surface is heated for 2 seconds, the inner peripheral surface is heated for 4 seconds, the inner peripheral surface is cooled for 4 seconds, and the inner peripheral surface is cooled. Assuming that the start of heating is 0.5 seconds after the end of the outer peripheral surface heating, the outer peripheral surface cooling is 8.5 seconds, and the time required for quenching one workpiece is 10.5 seconds. Therefore, the time is reduced by 2 seconds as compared with the conventional induction hardening method.

Next, the quenching method according to claim 1 will be described with reference to FIG. In this method, the capacity of the transformer 55 and the high-frequency power supply 56 has room, and the energizing of the outer peripheral surface hardening coil 10 and the inner peripheral surface hardening coil 20 can be performed at the same time. Applied to

That is, the heating of the inner peripheral surface 103 also starts simultaneously with the heating of the outer peripheral surface 101, but the heating time of the outer peripheral surface 101 is the first.
The heating time of the inner peripheral surface 103 is shorter than in the method of
Is the same length as in the quenching method. And the outer peripheral surface
Immediately after the heating of 101 is completed, cooling of the outer peripheral surface 101 is started. In addition, immediately after the inner peripheral surface 103 is heated, the inner peripheral surface 103 is cooled. The cooling of the outer peripheral surface 101 is continued until the cooling of the inner peripheral surface 103 is completed.

As an example of the duration of each step of the above quenching operation, as shown in FIG. 4, if the outer peripheral surface heating is 1.5 seconds, the inner peripheral surface heating is 4 seconds, and the inner peripheral surface cooling is 4 seconds, Surface cooling is 6.5 seconds, and the quenching time for one workpiece is 8 seconds, which is 4.5 seconds shorter than the conventional quenching method.

In this quenching method, cooling of the outer peripheral surface 101 is not started at the same time as heating of the inner peripheral surface 103 is started.
Relatively early after the start of heating the inner peripheral surface 103, that is, for example, 1.5
Since cooling of the outer peripheral surface 101 is started after a lapse of seconds, it is possible to prevent the quenching depth of the inner peripheral surface 103 from becoming too deep or hard quenching.

When the quenching method according to claim 1 is performed, the quenching depth of the inner peripheral surface 103 may be increased, the quenching may be excessive, or the distortion may need to be controlled. In the quenching method according to the second aspect, as shown in FIG. 5, the start of heating the inner peripheral surface 103 is delayed by, for example, one second from the start of heating the outer peripheral surface 101. Then, the inner peripheral surface 10
After the start of the heating of 3, for example, when 0.5 seconds have elapsed, the cooling of the outer peripheral surface 101 is started. In this case, the required quenching time of one workpiece is 9 seconds, which is 1 second longer than the quenching method according to claim 1, but 1.5 seconds shorter than the first quenching method. .

[0027]

As described above, the conventional induction hardening method for quenching the inner and outer peripheral surfaces of a thin ring-shaped work is performed by first quenching the inner peripheral surface while cooling the outer peripheral surface, and then quenching the outer peripheral surface. In contrast, in the induction quenching method of the present invention, since the cooling in the quenching of the outer peripheral surface and the cooling of the outer peripheral surface during the quenching of the inner peripheral surface are simultaneously performed, the quenching time is greatly increased. There is an effect that the length can be shortened and the distortion can be controlled.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of an embodiment of an induction hardening apparatus capable of realizing a method of the present invention.

FIG. 2 is an electric circuit diagram of one embodiment of an induction hardening device capable of realizing the method of the present invention.

FIG. 3 is a method of quenching a workpiece by the induction hardening apparatus shown in FIG.
It is a time chart which shows an example of a law .

[4] according to claim 1, wherein by induction hardening apparatus shown in FIG. 1
5 is a time chart of the work hardening method.

[5] according to claim 2, wherein by induction hardening apparatus shown in FIG. 1
5 is a time chart of the work hardening method.

FIG. 6 is a time chart of a conventional induction hardening method.

[Explanation of symbols]

 10 Hardening coil for outer surface 20 Hardening coil for inner surface 100 Work 101 Outer surface 103 Inner surface L, R Coolant

Claims (2)

(57) [Claims] 1. An induction hardening method for a thin-walled ring-shaped work having an outer peripheral surface and an inner peripheral surface, wherein the inner peripheral surface is hardened by an annular inner peripheral surface hardening coil disposed to face the inner peripheral surface . A first step of heating, and after the first step ,
A second step of cooling the peripheral surface, and a step of facing the outer peripheral surface.
Of the outer peripheral surface by an annular outer peripheral surface quenching coil
Heating is started at the same time as the start of the first step, and in the middle of the first step
A third step ending with
Quenching liquid from the outer surface hardening coil until the end
And a fourth step of cooling the outer peripheral surface by injecting the thin-walled work into a thin ring-shaped workpiece. 2. An induction hardening method for a thin ring-shaped work having an outer peripheral surface and an inner peripheral surface, wherein the inner peripheral surface is hardened by an annular inner peripheral surface quenching coil disposed so as to face the inner peripheral surface. A first step of heating, after the first step, a second step of cooling the inner peripheral surface, and heating of the outer peripheral surface by an annular outer peripheral surface quenching coil disposed to face the outer peripheral surface. A third step which starts before the first step and ends in the middle of the first step, and after the third step, the quenching liquid is discharged from the outer peripheral surface quenching coil until the second step is substantially completed. And cooling the outer peripheral surface by spraying onto a surface.