JPH1025519A - Induction hardening method of annular work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction hardening method of an annular work, by which the draw-out of a core metal is facilitated while preventing the deformation of the annular work in the induction hardening of the annular work and further, the hardened layer having uniform depth is obtd. on the whole outer peripheral surface of the annular work. SOLUTION: A metallic ring member 6 is fitted into a recessed part 2a of the core metal 2, and in the case the outer diameter of the core metal 2 is small so as to be shiftable to the radiating direction of core metal divided pieces 2b, when the core metal divided pieces 2b complete to shift to the center direction, the annular work W is laid on the upper surface of the metallic ring member 6 while forming a prescribed gap between the core metal 2 and the work. At the time of induction- heating, the induced heating current is generated in the annular work W and at the same time, the integral current circuit is formed with the metallic ring member 6 in the outer peripheral part of each of the core metal divided pieces 2b and the gap part of each of the core metal 2 and acted as an auxiliary current circuit. Then, the induced current generated in the annular work W is uniformized over the whole periphery and the internal holding heat in the annular work W is absorbed and dispersed to obtain the uniform hardened layer on the outer peripheral surface of the annular work W.

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 an annular work, in which a core metal is inserted into a hole of the annular work to prevent the deformation of the work and to perform induction heating and cooling.

[0002]

2. Description of the Related Art Conventionally, in a method of induction hardening an annular work, in which a core metal is inserted into a hole of an annular work to prevent deformation thereof, and then induction-heated, and then cooled with a refrigerant, an annular work is heated before induction heating. In the hole, the metal core is inserted by raising and lowering it with a cylinder or the like to support it from the inner peripheral surface side of the annular work to prevent deformation, conduct induction heating treatment, introduce refrigerant and heat the induction heated annular work. After cooling, the core is lowered and pulled out.

At this time, the hole diameter of the quenched annular work may be smaller than that before quenching due to thermal expansion. For this reason, when the core is pulled out, it may be difficult to pull out the core, or the inner peripheral surface of the annular work may be damaged due to the pull out of the core. For this reason, the core metal having a smaller outer diameter than the inner diameter of the annular work is divided into a plurality of pieces in the radial direction, and the gap between the divided pieces of the core metal is narrowed when inserting and removing the annular work, thereby reducing the outer diameter of the core metal. In addition, from the start of induction heating to the end of cooling, the outer diameter of the metal core is enlarged by expanding the gap between the divided pieces of the metal core, and the inner peripheral surface of the annular workpiece is supported and fixed.

[0004]

However, in such a conventional induction hardening method for an annular work, during induction heating and cooling, the inner peripheral surface of the annular work opposed to the gap between the cored metal pieces, In the inner peripheral surface of the annular work that comes into contact with the quenching, the quenched and hardened layer depth varies. That is, in the portion of the annular work facing the gap between the cored metal pieces, there has been a problem that the quench hardened layer is deeper than the inner peripheral surface of the annular work in contact with the cored metal pieces.

[0005] This is because the induction current generated in the annular work becomes non-uniform when the outer peripheral surface of the annular work whose inner peripheral surface is fixedly supported by the core metal having a gap between the core metal divided pieces is induction-heated. It is. That is, the inner peripheral surface of the annular work has a portion that is in contact with the core metal and a portion that is not in contact, and the induced current increases in the portion that is not in contact.

In addition, in the portion of the annular work that comes into contact with the cored metal pieces, the heat retained inside the annular work is absorbed and radiated to the cored metal pieces by heat conduction during induction heating. This is because the phenomenon does not occur in the portion of the opposed annular work, so that the depth of the quench-hardened layer varies during cooling after induction heating.

[Object] The object of the present invention is to prevent deformation of an annular work in induction hardening of the annular work while preventing the deformation of the work.
An object of the present invention is to provide an induction hardening method for an annular work that facilitates pulling out a metal core and further obtains a hardened layer having a uniform depth on the entire outer peripheral surface of the annular work.

[0008]

In order to solve the above-mentioned problems, an induction hardening method for an annular work according to the present invention is directed to a method for forming a plurality of cores into a concave portion provided on an outer peripheral surface of a metal core inserted into a hole of the annular work. A metallic annular member is fitted, an annular work is placed on the upper surface of the metallic ring member, and the annular work is induction-heated by an induction heating coil provided on the outer periphery of the annular work. Quenching is performed by cooling.

The metal core has a concave portion on its outer peripheral surface and is divided into a plurality in the radial direction. When the metal core is inserted into the hole of the annular work, the core metal is moved in the center direction between the divided pieces of the metal core. The outer diameter of the cored bar is made smaller than the inner diameter of the hole of the annular work, so that the cored bar can be easily inserted into the hole of the annular work. Further, during induction heating and cooling of the annular work, the outer diameter of the core is reduced by moving the divided pieces in the radial direction, thereby facilitating the extraction of the core from the annular work hole.

The metallic annular member forms an integral current path when the annular workpiece is induction-heated by the induction heating coil. Further, when an annular work is placed on the upper surface of the annular member and induction heating is performed, heat held inside the annular work is absorbed by heat conduction. Therefore, the material of the metallic annular member is preferably a material such as copper, which is conductive and has good thermal conductivity. The width of the metallic annular member is set such that when the annular work is placed on the upper surface thereof, the desired depth of the hardened layer of the annular work does not contact the annular member. That is, when the entire lower surface of the annular work comes into contact with the metallic annular member, the heat retained inside the annular work is absorbed and dissipated in the metallic annular member, so that a desired hardened hardened layer cannot be obtained on the outer periphery of the annular work. Because.

In the case where the core metal divided piece is moved in the center direction to reduce the outer diameter of the core metal so that the core metal divided piece can be moved, the core metal and the metallic annular ring may be moved. A predetermined gap is formed between the members.

Further, the induction heating coil is disposed on the outer periphery of the annular work, and induction-heats the outer periphery of the annular work.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 to 7 show an embodiment of an induction hardening apparatus to which the present invention is applied.

First, the configuration will be described.

FIG. 1 shows an induction hardening apparatus 1 according to the present embodiment.
It is sectional drawing which shows the principal part structure of. In FIG. 1, an induction hardening device 1 includes a divided core 2, a core moving mechanism 3 for moving the core 2 in the direction of the arrow in the figure, and a core 2.
An induction heating coil 4 for inductively heating an annular work W (not shown), which is a member to be quenched, fixed by the above, a pressing mechanism 5 for suppressing upward deformation of the annular work in the figure, and a split piece of the cored bar 2 And a metallic ring member 6 fitted into the concave portion of the cored bar 2 when moving in the radially expanding direction of 2b.

The cored bar 2 shown in FIG. 1 is divided into three in the radial direction as shown in the plan view of FIG. 2 to form a cored bar 2b, and each cored bar 2b is arranged at a predetermined interval on a concentric circle. When moved by the cored bar moving mechanism 3 in the direction of the arrow shown in FIGS. 1 and 2, the annular workpiece W which is a quenched member set on the outer periphery thereof is arranged. Each cored bar 2b supports and fixes the inner peripheral surface to prevent deformation of the annular workpiece W during induction heating and cooling. Further, when the cored bar split piece 2 is moved by the cored bar moving mechanism 3 in a direction to reduce the outer diameter of the cored bar 2, there is sufficient space between the outer peripheral surface and the inner peripheral surface of the annular work W. A gap is formed to facilitate pulling out of the metal core 2 from the annular workpiece W. In addition, a concave portion 2a is formed on the outer periphery of each core metal divided piece 2b so that the metallic ring member 6 is fitted.

The moving rod 3e has a distal end formed in a conical shape, and is driven up and down by a drive mechanism (not shown).
The movable member 3b against the urging force is pushed and expanded in the left-right direction in the drawing to move in the radially increasing direction.

As shown in FIG. 1, the core metal moving mechanism 3 includes a case 3a and a moving member 3 housed in the case 3a.
b, fixing member 3 for fixing core 2 to moving member 3b
c, a spring 3d for urging the moving member 3b in the direction of the central axis in the figure to move the moving member 3b in the radially-reducing direction, and moving the moving member 3b upward in the figure so as to move the moving member 3b by the conical shape of the tip thereof And a moving rod 3e that is pushed in the left-right direction and moved in the radially increasing direction.

As shown in the plan view of FIG. 1, the moving member 3b is fixed together with the fixing member 3c for each of the three divided metal cores 2, and the end of each moving member 3b in the direction of the central axis has a moving rod. 3e is formed in a tapered shape so as to be in contact with the conical shape of the tip portion. Therefore, the moving member 3b
Due to the upward movement of the moving rod 3e, the moving rod 3e is pushed and expanded against the urging force of the spring 3d due to the conical shape at the distal end thereof, and is uniformly moved in the radially expanding direction.

The spring 3d is provided for each of the three moving members 3b in the case 3a, one end of which is fixed to the inner wall of the case, and the other end of which contacts the moving member 3b.
Energize b. When the moving rod 3e is lowered, the spring 3d moves the moving member 3 in the central axis direction in the drawing when the moving rod 3e is extended.
When the moving rod 3e is moved upward by urging the moving member 3b in the diameter reducing direction, the moving member 3b is contracted as the moving member 3b moves in the diameter expanding direction.

The fixing member 3c is interposed between the metal core 2 and the moving member 3b for each of the three divided metal cores 2 and fixes the metal core 2 and the moving member 3b with a fixing bolt or the like (not shown). The cored bar 2 is moved with the movement of the moving member 3b.

The moving rod 3e has a distal end portion formed in a conical shape, and is moved up and down by a drive mechanism (not shown).
The movable member 3b against the urging force is pushed and expanded in the left-right direction in the drawing to move in the radially increasing direction.

The induction heating coil 4 is for inductively heating the outer peripheral surface of an annular workpiece (for example, a gear) as a member to be hardened, and is alternately driven by a predetermined high-frequency current supplied from a high-frequency power supply (not shown). A magnetic flux is generated, an induction current is generated on the outer peripheral surface of the annular work W, induction heating is performed, and then the annular work W is cooled to form a quenched and hardened layer on the outer peripheral surface of the annular work W.

The presser mechanism 5 is raised and lowered by a drive mechanism (not shown), and presses the upper surface of the annular work W supported and fixed to the cored bar 2 from above over the entire circumference by the lowering movement, thereby performing induction heating and heating. The upward deformation of the annular work W during cooling is suppressed.

The metallic ring member 6 is provided with the concave portion 2 a of the cored bar 2.
When the outer diameter of the cored bar 2 is small so as to be fitted into the concave portion 2a of the cored bar 2 and to allow the cored bar 2b to move in the radial direction, that is, the cored bar 2b After completing the movement in the center direction, a predetermined gap is formed between the metal core 2 and the metal core 2. An annular workpiece W is placed on the upper surface of the metallic ring member 6. At the time of induction heating of the annular work W, an induction heating current is generated in the annular work W, and at the same time, an integral current is formed by the metallic ring member 6 also in the outer peripheral portion of each cored bar piece 2b and the gap between the cored bars 2. A path is formed. That is, the metallic ring member 6 acts as an auxiliary current path, and averages the amount of induced current generated in the annular work W over the entire circumference.

After cooling the annular work W, a uniform hardened layer is formed on the outer peripheral surface of the annular work W regardless of the presence or absence of the gap between the cored metal pieces 2b. Therefore, it is not preferable that the metallic ring member 6 be brought into contact with the desired width of the hardened hardened layer of the annular work W. That is, since the portion of the annular workpiece W that comes into contact with the metallic ring member 6 is deheated as described above, there is a possibility that the quenched and hardened layer is not formed.

Next, the operation of this embodiment will be described.

The operation of the core 2 and the core moving mechanism 3 during the induction heating of the annular workpiece by the induction hardening apparatus 1 of FIG. 1 will be described with reference to FIGS.

First, FIG. 3 shows that an annular work W as a material to be quenched is inserted into a three-piece cored metal 2 and placed and set on a metallic ring member 6 in an induction hardening apparatus 1. At this time, the conductive ring member 6 is prevented from contacting the portion Wa of the annular workpiece W where the quench hardened layer is desired. Further, since the divided piece 2b of the cored bar 2 moves in the direction of the arrow in the figure, the outer diameter of the cored bar 2 is smaller than the inner diameter of the annular work W.

At this time, the moving rod 3 of the cored bar moving mechanism 3
e is fixed downward in the figure, and the moving member 3b is urged in the direction of the central axis in the figure by the urging force of the spring 3d, so that the outer diameter is small. The annular workpiece W is set at a predetermined position between the induction heating coil 4 and the metal core 2 in a state where the diameter of the metal core 2 is reduced.

FIG. 4 shows a state in which the annular workpiece W set in the induction hardening apparatus 1 is being subjected to induction heating and cooling. At this time, the outer diameter of the core metal 2 is enlarged by moving the divided piece 2b of the core metal 2 in the direction of the arrow in the figure in advance, and the inner peripheral surface of the annular work W is supported and fixed, thereby performing induction heating and cooling. Deformation is prevented. The movement of the cored bar 2 is performed by moving the moving member 3b in the direction of the arrow in the drawing by the movement of the moving shaft 3e having a tapered tip, and accompanying this, the fixing member 3c fixed on the moving member 3b with bolts or the like. The moving member 3b and the metal core 2 bolted to the moving member 3b move in the direction of the arrow.

The holding mechanism 5 descends from above the annular work W almost simultaneously with the movement of the cored bar 2, and supports and fixes the upper surface of the annular work W while pressing the upper surface of the annular work W over the entire circumference. Prevents upward deformation during induction heating and cooling. The metallic ring member 6 is fitted into a concave portion 2 a provided on the outer peripheral surface of the cored bar 2. Further, as shown in FIG. 2, a gap 2c is formed between the cored bar divided pieces 2b.

The induction heating coil 4 is arranged at a predetermined interval on the outer periphery of the annular work W, inductively heats the outer peripheral surface of the annular work W, and immediately thereafter, a coolant injected from a coolant spray jacket (not shown). Thereby, the heated portion of the annular work W is cooled, and a quenched and hardened layer is formed. After the induction hardening, the state shown in FIG. 5 is obtained. That is, the outer diameter of the core metal 2 is made smaller than the inner diameter of the annular work W by moving the divided piece 2b of the core metal 2 toward the center again, and the core metal 2 is easily pulled out.

The movement of the metal core piece 2b is caused by lowering the moving shaft 3e, whereby the moving member 3b moves in the direction of the arrow in FIG. At this time, since the moving member 3b is urged by the extension of the compression coil spring 3d, the movement of the metal core 2 becomes possible only by the lowering of the moving shaft 3e.

As described above, in the induction hardening apparatus 1 according to the present embodiment, the core metal 2 for preventing the deformation of the annular work W during the cooling process is divided into three to form a divided piece 2b. A gap 2c is formed between the gold split pieces 2b, and the core metal 2 divided into three parts can be evenly moved by the core metal moving mechanism 3 in the direction of decreasing the outer diameter and the direction of increasing the outer diameter. In addition, at the time of cooling, the deformation of the annular work W can be prevented by moving the outer diameter of the cored bar 2 in a direction in which the outer diameter of the cored bar 2 is enlarged. Is moved in a direction to reduce the size of the annular work W, which is the member to be heated, and the annular work W
The core metal 2 can be easily removed from the core.

For this reason, in the induction hardening device 1,
It is possible to prevent the core metal 2 from being hardly removed from the annular work W after the induction heating and cooling of the annular work W, and to prevent the inner peripheral surface of the annular work W from being damaged when the core metal 2 is removed. As a result, the reliability of the induction hardening device 1 for induction heating the annular workpiece W can be improved.

Also, a concave portion 2a provided in each core metal segment 2b.
The metal ring member 6 is fitted so that the metal ring member 6 is fitted into the concave portion 2a of the metal core 2 and the core metal split piece 2b can be moved in the radial direction. When the outer diameter of the cored bar 2 is small, that is, after the cored bar 2b has moved toward the center, a predetermined gap is formed between the cored bar 2 and the cored bar 2. An annular workpiece W is placed on the upper surface of the metallic ring member 6. At the time of induction heating of the annular work W, an induction heating current is generated in the annular work W, and at the same time, an integral current is formed by the metallic ring member 6 also in the outer peripheral portion of each cored bar piece 2b and the gap between the cored bars 2. A path is formed. That is, the metallic ring member 6 acts as an auxiliary current path, averages the amount of induced current generated in the annular work W over the entire circumference, and absorbs and disperses the heat internally held by the induction heating of the annular work W. As a result, a uniform hardened and hardened layer can be obtained on the outer peripheral surface of the annular work W.

Here, the ring-shaped workpiece W is divided into a case where the metal ring member 6 is not applied to each cored bar 2 during the heat treatment and a case where the metal ring member 6 is applied to each cored bar 2b. FIGS. 6 and 7 show an example of the quenched layer formed in FIG. 6 and 7 show an example in which a gear is induction-heated as the annular work W.

FIG. 6 shows an example of a quench hardened layer formed on a part of a gear as an annular work W when induction heating is performed without applying the metallic ring member 6 to each cored bar piece 2b. Is shown. In this case, the core metal split piece 2b of the gear
The portion of the quench hardened layer facing the gap portion between the gaps is deepened, and the "submerged" state occurs. This is because an auxiliary current path is not formed by the metallic ring member 6, so that a portion of the annular work W facing the gap 2 c of the cored bar divided piece 2 b is
This is caused by an increase in the amount of induction current generated by the induction heating coil 4.

FIG. 7 shows the quenched and hardened layer formed on a part of the gear as the annular work W when the metallic ring member 6 is applied to each cored bar piece 2b and induction heating is performed. An example is shown. In this case, the depth of the quenched hardened layer at the portion facing the gap 2c between the cored metal divided pieces 2b of the gear is the same as the depth of the quenched hardened layer formed at the portion not facing the other gap 2c. is there. This is the metallic ring member 6
Is formed, the portion of the annular work W facing the gap 2c between the cored bar divided pieces 2b and the other gap 2
This is because the amount of induction current generated by the induction heating coil 4 is averaged even in the portion not facing c, thereby preventing the occurrence of the "burn-through" state as shown in FIG.

During the induction heating and cooling, the annular work W is supported and fixed on the inner peripheral wall side by the cored metal piece 2b, so that the deformation in the radial direction is prevented, and the holding mechanism 5 is held. By being pressed from above, the upward deformation is prevented.

FIG. 5 shows the state of the core 2 and the core moving mechanism 3 after induction heating of the annular workpiece W set in the induction hardening apparatus 1. At this time, the core moving mechanism 3
The moving rod 3e is moved downward in the figure by the drive mechanism, and the moving member 3b is urged in the direction of the central axis in the figure by the urging force of the spring 3d to reduce the diameter. In the state where the diameter of the cored bar 2 is reduced, a sufficient gap is formed between the cored bar 2 and the annular work W, so that the annular work W can be easily taken out or the cored bar 2 can be easily removed from the annular work W. .

As described above, in the induction hardening apparatus 1 of the present embodiment, the metal core 2 for preventing deformation of the annular work W during induction heating and cooling is divided into three parts to form a divided piece 2b. A gap is formed on the circumference, and the core metal 2 divided into three parts can be evenly moved in the diameter reducing direction and the diameter increasing direction by the core metal moving mechanism 3, so that during the induction heating process and the cooling process, By moving the cored bar 2 in the radially expanding direction, deformation of the annular work can be prevented. Before and after the induction heating process and the cooling process, the cored bar 2 is moved in the radially reduced direction to be heated. It is possible to easily set the annular work as a member and extract the core metal from the annular work.

Therefore, in the induction hardening device 1,
It is possible to prevent the core metal from being easily removed from the annular work after the induction heating process and the cooling process of the annular work, and to prevent the inner peripheral surface of the annular work from being damaged when removing the core metal.

As a result, the reliability of the induction hardening apparatus 1 for induction heating the annular workpiece W can be improved.

In the induction hardening apparatus 1 of the present embodiment, the frequency during induction heating is appropriately set while the quenched annular workpiece W is supported and fixed by the cored bar 2 and the holding mechanism 5. The annular workpiece W can be tempered by performing induction heating and cooling again.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say, there is. For example, in the above-described embodiment, the case where the cored bar 2 is configured by three divisions has been described, but the number of divisions is not limited, and the number of divisions is set so that the structure of the cored bar moving mechanism 3 is not more complicated. May be increased.

The configuration of the cored bar moving mechanism 3 of the above embodiment is not limited, and can be changed to various configurations as long as the purpose of moving the cored bar 2 can be achieved. .

[0050]

The induction hardening method for an annular work according to the present invention is characterized in that a metal core is divided into a metal ring and a metal ring fitted to the outer peripheral surface of the metal core to facilitate removal of the annular work after induction heating and cooling. The amount of induced current generated in the annular work by the member can be averaged over the entire circumference, and the heat retained inside by the induction heating of the annular work is absorbed and diverted to the metallic ring member, so that the outer peripheral surface of the annular work is A uniform quench-hardened layer can be obtained.

Further, according to the induction hardening method for an annular work of the present invention, the frequency at the time of induction heating is appropriately set while the annular work after quenching is supported and fixed by the metal core and the pressing mechanism, and the induction heating is performed again. It is also possible to temper the annular work by performing cooling.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main configuration of an induction hardening apparatus to which the present invention is applied.

FIG. 2 is a plan view of the metal core of FIG. 1 as viewed from above.

FIG. 3 is a view showing a state of a metal core and a metal core moving mechanism when an annular work is set in the induction hardening apparatus of FIG. 1;

FIG. 4 is a diagram showing a state of a core bar and a core bar moving mechanism during induction heating of an annular workpiece in the induction hardening apparatus of FIG. 1;

FIG. 5 is a diagram showing a state of a core metal and a core metal moving mechanism after induction heating treatment of an annular work in the induction hardening apparatus of FIG. 1;

FIG. 6 is a view showing an example of a quenched layer of an annular workpiece which has been heated without applying a fitting member to the core metal of FIG. 1;

FIG. 7 is a view showing an example of a quenched layer of an annular work which has been heated by applying a fitting member to the core metal of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 induction hardening device 2 core metal 2a recess 2b core metal split piece 2c gap 3 core metal moving mechanism 3a case 3b moving member 3c fixing member 3d spring 3e moving rod 4 induction heating coil 5 holding mechanism 6 metal ring member W annular work

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication C21D 1/42 C21D 1/42 GM 1/62 1/62 (72) Inventor Takashi Kikuchi Aichi 77-41, Hachiman-mae, Kutsukake-cho, Toyoake-shi Nagoya Factory

Claims (1)

[Claims] An outer diameter of the metal core is increased by inserting a plurality of cores divided radially into a hole of an annular work and expanding a gap between the divided pieces of the metal core. The inner peripheral surface of the work is supported and fixed by the divided pieces, and the outer peripheral surface of the annular work is induction-heated by an induction heating coil provided on the outer periphery of the annular work, and then cooled by a refrigerant to quench the annular work. In the induction hardening method for an annular work, the upper surface of the annular work is supported and fixed while being pressed by a support member lowered from above the annular work, and a concave portion is provided on the outer peripheral surface of the core metal divided into a plurality of portions. An induction hardening method for an annular work, comprising mounting the annular work as a member to be hardened on a metallic annular member having electrical and thermal conductivity.