WO2011007434A1

WO2011007434A1 - Induction heating coil for carburizing and carburizing system

Info

Publication number: WO2011007434A1
Application number: PCT/JP2009/062827
Authority: WO
Inventors: 亮介山本; 節夫黒松
Original assignee: 光洋サーモシステム株式会社; 株式会社黒松電機製作所
Priority date: 2009-07-15
Filing date: 2009-07-15
Publication date: 2011-01-20
Also published as: CN102471816A; JP5464611B2; JPWO2011007434A1

Abstract

Disclosed is an induction heating coil (7) configured to induction heating a pulley shaft (1) having a disk-like pulley portion (3) and a shaft portion (2) over a wide range for carburizing, wherein the configuration can be simplified. The induction heating coil (7) is equipped with a first coil portion (10) for induction heating at least the shaft portion (2), and a second coil portion (20) provided around the pulley portion (3) from the front surface (4) across the back surface (5) thereof and induction heating the pulley portion (3). The first coil portion (10) and the second coil portion (20) are integrated in series.

Description

Induction heating coil and carburizing apparatus for carburizing process

The present invention relates to an induction heating coil for carburizing treatment and a carburizing treatment apparatus provided with the induction heating coil.

2. Description of the Related Art A belt-type continuously variable transmission (hereinafter referred to as CVT) is known as a transmission mounted on an automobile, and this CVT includes a driving side and a driven side pulley device, a power transmission chain, and the like. Each of the pulley devices includes a pulley shaft integrally including a shaft portion and a disk-like pulley portion, and a pulley that can be displaced along the shaft portion.
In the pulley shaft, as disclosed in Japanese Patent Laid-Open No. 9-25519, in order to improve durability and the like, a high-frequency quenching process in which the pulley shaft is partially heated for a short time and rapidly cooled is performed. There is.

However, a high surface pressure acts on the sliding surface of the pulley shaft belt, and a load acts repeatedly on the entire pulley shaft. Therefore, in order to extend the fatigue life, the heat treatment is more carburized than the quenching treatment. It may be preferable to perform the treatment.
2. Description of the Related Art Conventionally, as a device for performing a carburizing process, there is a device including a batch type or continuous type heating furnace that heats a workpiece by an internal heater.

When carburizing the pulley shaft, it is necessary to uniformly heat and hold the entire pulley shaft for an arbitrary predetermined time. However, since the pulley shaft has a shaft portion and a disk-like pulley portion and has a complicated shape, the carburizing treatment by the heating furnace has a limited load capacity for the carburizing treatment of the pulley shaft having such a shape. May not be suitable. Moreover, even if the induction hardening coil used for the partial heating for a short time is used for the carburizing process, good results cannot be obtained.
Therefore, as shown in FIG. 13, the inventor has a plurality of

coils

91, 92, 93, 94, 95 provided according to the shape of the pulley shaft 90, and a power supply unit 96 provided for each of these coils. And tried to inductively heat each part of the pulley shaft 90.
However, in this case, the pulley shaft 90 can be heated and held in a wide range for a long time, but it has not been heated uniformly. That is, the temperature near the boundary between the shaft portion and the pulley portion was particularly high, but the tendency was found that the temperature of the belt sliding surface of the pulley portion was lowered as it approached the outer peripheral end portion. In addition, this configuration requires a plurality of power supply units 96, increasing the initial cost of the apparatus, making it difficult to install the

coils

91, 92, 93, 94, 95 on the pulley shaft 90, and improving workability. I faced the problem of poor productivity and low productivity.

Therefore, the present invention is not configured to partially heat the pulley shaft for a short time as in the induction hardening process, but to be configured to uniformly heat the pulley shaft over a wide range for a long time in order to perform the carburizing process. It is another object of the present invention to provide an induction heating coil for carburizing treatment that can simplify the configuration for carburizing treatment and a carburizing treatment apparatus including the induction heating coil.

In order to achieve the above object, the present invention provides an induction heating coil for carburizing a pulley shaft having a disk-shaped pulley portion and a shaft portion on the same center line, and at least the shaft portion is guided. A first coil part for heating, and a second coil part for inductively heating the pulley part provided around the pulley part across the front surface to the back surface of the pulley part, the first coil part And the second coil part are integrated in series.

According to the present invention, the first coil portion is for induction heating of at least the shaft portion, and the second coil portion is for induction heating of the pulley portion, so that the pulley shaft is heated in a wide range. Can be carburized. In particular, since the second coil portion is provided around the pulley portion from the surface of the pulley portion to the back surface, it is possible to carburize both the front surface and the back surface of the pulley portion.
And since it is the structure which can heat a pulley shaft in a wide range in this way, and since the 1st coil part and the 2nd coil part are integrated in series, the 1st coil and the 2nd coil Can be shared, and the configuration of the apparatus for carburizing can be simplified.

Further, the first coil portion is formed by connecting a pair of axial line portions extending in a direction parallel to the shaft portion and sandwiching the shaft portion therebetween, and an axial line portion forming the pair. And a detour portion that curves around the center line side and opens the end surface of the shaft portion in the axial direction.
When carburizing the pulley shaft, it is necessary to support the pulley shaft having an axial shape, but according to the bypass line, the end surface of the shaft portion of the pulley shaft is open in the axial direction. The pulley shaft can be supported by sandwiching the shaft portion from both outer sides in the axial direction.

Moreover, it is preferable that the space which can take in and out the said pulley shaft is formed toward the one direction orthogonal to the said center line from said 1st coil part and said 2nd coil part.
According to this space, the pulley shaft is approached from the one direction without interfering with the first coil portion and the second coil portion of the induction heating coil, and the pulley shaft is surrounded by the induction heating coil. In addition, the pulley shaft at the predetermined position can be separated from the induction heating coil and taken out in the one direction without interference. As a result, it is not necessary to install a coil as a preparatory work for performing the carburizing process, and automation is possible.

Further, the second coil portion has a front facing line portion facing the front surface of the pulley portion and a back facing line portion facing the back surface, and the front facing line portion and the back facing line portion are front and back. It is preferable to have an asymmetric structure that is an asymmetrical arrangement.
In this case, it becomes possible to perform carburizing treatment by induction heating both the front and back surfaces of the pulley portion by the front facing line portion and the back facing line portion, but in the portion where the thickness of the pulley portion is thin, There is a risk that the eddy current generated on the front surface and the back surface cancels each other and the heat generation amount is reduced. However, according to the asymmetric structure portion, since the front-facing line portion and the back-facing line portion are asymmetrically arranged on the front and back sides, it is possible to prevent eddy currents generated on the front surface and the back surface from canceling each other. For this reason, it can prevent that the emitted-heat amount becomes small in a thin part.

In addition, the first coil portion of the induction heating coil includes a portion for induction heating the shaft portion, and an extended portion extending from the shaft portion of the pulley portion to both sides in a direction perpendicular to the center line. It is preferable to have a part for induction heating.
According to this configuration, by the first coil portion, in addition to the shaft portion, a part of the pulley portion (the extending portion) can be induction-heated, and the pulley shaft is induction-heated in a wide range to be carburized. Can do.
A portion for induction heating of the shaft portion and a portion for induction heating of the extending portion can be induction-heated in such a wide range and the first coil portion has a simple configuration. May be arranged along a virtual plane including the center line and around the pulley shaft.

Further, the present invention provides an induction heating coil for carburizing a pulley shaft having a disk-shaped pulley portion and a shaft portion on the same center line, and the pulley shaft is heated and raised by the induction heating coil. And a control device that controls the temperature rising state to continue for a predetermined time after the temperature rise, and the induction heating coil includes at least a first coil portion for induction heating the shaft portion, and the pulley portion. And a second coil part provided around the pulley part for inductively heating the pulley part from the front surface to the back surface, wherein the first coil part and the second coil part are integrated in series. It is characterized by.

According to the present invention, in order to perform the carburizing process, the induction heating coil is configured to be able to uniformly heat and hold the pulley shaft over an arbitrary predetermined time in a wide range, and the first coil portion and the second coil Since the parts are integrally connected in a series arrangement, the power sources of the first coil and the second coil can be shared, and the configuration of the carburizing apparatus can be simplified.
Then, the pulley shaft can be carburized by heating the pulley shaft to raise the temperature and continuing the temperature rising state for a predetermined time.

In addition, the control device is configured to prevent the eddy current generated on the front surface side of the pulley unit and the eddy current generated on the rear surface side from being canceled by the second coil unit. It is preferable to have a power source with a high frequency.
In this case, both the front and back surfaces of the pulley portion can be heated and carburized by the second coil. However, in the portion where the pulley portion is thin, the eddy current cancels out and the amount of heat generated May decrease. However, by making the current that the power supply gives to the induction heating coil at a high frequency, the penetration depth of the eddy current can be reduced, and it is possible to prevent the amount of heat generation from being reduced in the thin portion. Become.

It is explanatory drawing which has shown the outline of the carburizing processing apparatus provided with the induction heating coil of this invention. It is a top view of an induction heating coil and a pulley shaft. It is a bottom view of an induction heating coil and a pulley shaft. It is a rear view of an induction heating coil and a pulley shaft. It is a front view of an induction heating coil and a pulley shaft. It is a left view of an induction heating coil and a pulley shaft. It is a right view of an induction heating coil and a pulley shaft. It is a figure explaining the function of a carburizing control part. It is a figure explaining an induction hardening process (conventional example). It is sectional drawing of the edge part of a pulley part, and all the winding parts. It is explanatory drawing which has shown the outline of other embodiment of the carburizing processing apparatus of this invention. It is sectional drawing of the edge part of a pulley part, and all the winding parts. It is explanatory drawing of the carburizing processing apparatus provided with the induction heating coil made as an experiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an outline of a carburizing apparatus provided with an induction heating coil 7 of the present invention. The carburizing apparatus includes an induction heating coil 7 that heats the pulley shaft 1 and a controller 6 that performs control for carburizing process.
The pulley shaft 1 is made of, for example, chrome steel (SCr420), and has a disk-shaped pulley portion 3 and a shaft portion 2 as an integral unit. The pulley portion 3 and the shaft portion 2 are disposed on the same shaft core (hereinafter, this shaft core is referred to as a center line C).
In the present invention, the direction along the center line C is the Z-axis direction, the radial direction of the pulley portion 3 and one direction orthogonal to the Z-axis direction is the X-axis direction, and the radial direction of the pulley portion 3 is A direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis direction.

The induction heating coil 7 is wound around the pulley shaft 1 in order to carburize the pulley shaft 1. The induction heating coil 7 is supplied with a high frequency current from a power source 8 included in the control device 6, and induction heats the pulley shaft 1 with an induction current (eddy current) generated by the high frequency current.
The induction heating coil 7 includes

input line portions

30 and 31 having high-frequency input terminals, a first coil portion 10 connected to the input wire portion 30 for induction heating at least the shaft portion 2, and an input wire. It has the 2nd coil part 20 for being connected with the part 31 and carrying out the induction heating of the pulley part 3. FIG. In addition, although the 1st coil part 10 of this embodiment demonstrates later, the axial part in the pulley part 3 other than the part (axial direction line parts 11 and 12) for induction heating the axial part 2 is demonstrated. 2 also includes portions (half-winding portions 23 and 24) for induction heating the extending portions 3b extending from 2 to both sides in the direction orthogonal to the center line C (both sides in the Y direction). That is, in this embodiment, the 1st coil part 10 carries out the induction heating of the said extending | stretching part 3b of the pulley part 3 other than the axial part 2. FIG.
The induction heating coil 7 further includes a connection line portion 32 that connects the first coil portion 10 and the second coil portion 20.
The input terminals of the

input line portions

30 and 31 are connected to a cable (not shown) on the power source 8 side. The first coil portion 10 and the second coil portion 20 are electrically integrated in series via the connecting wire portion 32.

The first coil portion 10 has a pair of

axial line portions

11 and 12 for induction heating of the shaft portion 2. The

axial line portions

11 and 12 extend in a direction parallel to the shaft portion 2 (center line C) and are disposed so as to sandwich the shaft portion 2 in the Y-axis direction. Although the axial

direction line parts

11 and 12 are set longer than the length of the axial part 2, the

half winding parts

23 and 24 mentioned later for induction heating the said extending | stretching part 3b intervene in the middle part. ing. The first coil portion 10 is composed of a three-turn coil portion. In the axial

direction line portions

11 and 12, the direction of current flow is the Z-axis direction (positive direction and negative direction).
2 and 3 are a plan view and a bottom view of the induction heating coil 7 and the pulley shaft 1, respectively. The first coil portion 10 has a detour portion 13 on both ends of the pair of

axial line portions

11 and 12, and the detour portion 13 connects the pair of axial

direction line portions

11 and 12. In addition, the end surface 2a of the shaft portion 2 is opened outward in the axial direction by curving around the center line C side.

In addition, when carburizing the pulley shaft 1, it is necessary to support the pulley shaft 1. In particular, in this embodiment, since the pulley shaft 1 is heated by the induction heating coil 7 while rotating around the center line C, the pulley shaft 1 is supported by sandwiching the shaft portion 2 from both outer sides in the axial direction. preferable.
Therefore, according to the detour portion 13, since the end surface 2 a of the shaft portion 2 is opened to both outer sides in the axial direction, the pulley shaft 1 can be sandwiched by chuck portions (not shown) from both outer sides in the axial direction. . The pulley shaft 1 can be rotated by driving the chuck portion around the center line C.

4 and 5 are a rear view and a front view of the induction heating coil 7 and the pulley shaft 1, respectively. The pair of axial

direction line parts

11 and 12 are connected to a part for induction heating of the drawn line part 3b in the middle part thereof. That is, in FIG. 4, the first coil portion 10 is in a state in which, in addition to the

axial line portions

11 and 12, the stretched wire portion 3 b of the pulley portion 3 is substantially half-wrapped continuously with one axial line portion 11. And a semi-winding portion 24 which is in a state of being wound around the extending wire portion 3b of the pulley portion 3 substantially half a circle continuously with the other axial direction wire portion 12.
The

semi-winding portions

23 and 24 have a front facing line portion 21 and a back facing line portion 22 that face the front surface 4 and the back surface 5 of the pulley portion 3. The front opposing line portion 21 has a linear portion 23a and a linear portion 24a, and the back opposing line portion 22 has a linear portion 23b and a linear portion 24b.

In FIG. 5, the second coil portion 20 has an entire winding portion 27 that is in a state in which the pulley portion 3 (however, a portion other than the drawn wire portion 3 b) is wound one or more times. The entire winding portion 27 has a front facing line portion 25 and a back facing line portion 26 facing the front surface 4 and the back surface 5 of the pulley portion 3. The front facing line portion 25 has a linear portion 25 a that faces the surface 4 of the pulley portion 3, and the back facing line portion 26 has a linear portion 26 a that faces the back surface 5 of the pulley portion 3. ing.
As described above, the second coil portion 20 has the front facing line portion 25 facing the front surface 4 of the pulley portion 3 and the back facing line portion 26 facing the back surface 5.
The second coil part 20 is wound around the pulley part 3 across the front surface 4 to the back surface 5 of the pulley part 3 in order to heat the part of the pulley part 3 other than the drawn wire part 3b. ing.

In FIG. 1, each of the half-winding

portions

23 and 24 of the first coil portion 10 and the entire winding portion 27 of the second coil portion 20 is composed of three winding coil portions, and a linear portion of the half-winding portion 23. 23a and 23b (see FIG. 4), the

straight portions

24a and 24b of the half winding portion 24, and the

straight portions

25a and 26a (see FIG. 5) of the full winding portion 27, the direction of current flow is This is the Y-axis direction (positive direction and negative direction).

The front facing line portion 25 and the back facing line portion 26 of the entire winding portion 27 do not intersect the center line C and are parallel to the Y direction. That is, it is in a twisted position with respect to the center line C. The

semi-winding portions

23 and 24 are arranged along the same virtual plane (YZ plane) as the

axial line portions

11 and 12, and the linear portions of the

semi-winding portions

23 and 24 are Y It is parallel to the radial direction of the pulley portion 3 in the axial direction.
6 and 7 are a left side view and a right side view of the induction heating coil 7 and the pulley shaft 1. The full winding portion 27 is provided only on one side in the X-axis direction with respect to the

half winding portions

23 and 24.

As shown in FIG. 4, the pulley shaft 1 is surrounded by the first coil portion 10 and the second coil portion 20 and viewed from the back (one direction orthogonal to the center line C (the negative direction of the X axis). )), The windings of the

axial line portions

11 and 12 and the

semi-winding portions

23 and 24 are arranged around the pulley shaft 1 so that the entire pulley shaft 1 can be seen. That is, a space in which the pulley shaft 1 can be taken in and out is formed from the first coil portion 10 and the second coil portion 20 from the back side (from one direction orthogonal to the center line C (negative direction in the X-axis direction)). Yes.
According to this space, the pulley shaft 1 can be approached from the back side without interfering with the induction heating coil 7, and the pulley shaft 1 can be installed at a predetermined position surrounded by the induction heating coil 7. In addition, the pulley shaft 1 at the predetermined position can be separated from the induction heating coil 7 toward the back side and taken out without interference. As a result, the carrying-in and carrying-out before and after the carburizing process can be automated and performed quickly.
As shown in FIG. 5, when viewed from the front, the entire winding portion 27 is provided across the shaft portion 2 of the pulley shaft 1 in the Y direction. For this reason, it is impossible to take in and out the pulley shaft 1 from the front side.

Regarding the configuration of the induction heating coil 7, the order from one input line portion 30 to the other input line portion 31 will be described. In FIG. 4, one input line portion 30, the upper portion of the axial direction line portion 12, and half winding Part 24, lower part of the axial line part 12, lower bypass part 13, lower part of the axial line part 11, half-winding part 23, upper part of the axial line part 11, upper bypass part 13, The pulley shaft 1 is surrounded by one coil portion by each line portion. And each said wire | line part is continuously arranged similarly, and the structure of 3 windings is obtained, The above part becomes said 1st coil part 10. FIG. In FIG. 6, the upper part of the third axial line part 11 is connected to the upper part of the connection line part 32.

In FIG. 1, the lower portion of the connection line portion 32 is connected to the entire winding portion 27 and the linear portion 25 a of the front facing line portion 25, and the entire winding portion 27 rotates the pulley portion 3 counterclockwise. Wind three times. The entire winding portion 27 is configured such that the pulley portion 3 is wound three times while being displaced in the X-axis direction every round. This portion after the lower portion of the connecting wire portion 32 becomes the second coil portion 20. The other input line portion 31 is connected to the end portion of the entire winding portion 27.
As described above, the induction heating coil 7 is drawn from one input line portion 30 to the other input line portion 31 through the first coil portion 10, the connection wire portion 32, and the second coil portion 20. It has a configuration. Moreover, each line part of the induction heating coil 7 of the embodiment has a shape (rectangular shape) with a flat cross section.

In FIG. 1, the control device 6 has a storage unit 6 a composed of a storage device such as a RAM or a ROM, and stores a computer program for carburizing processing executed by the control device 6. And the control apparatus 6 is provided with the carburizing control part 6b as a functional part achieved by running the said computer program. The carburization control unit 6b is configured to control the power supply circuit unit including the power supply 8 in order to control the time, timing, current value, frequency, and the like of applying an alternating current to the induction heating coil 7.

FIG. 8 is a diagram for explaining the function of the carburization control unit 6b that performs the carburizing process using the induction heating coil 7, and shows a state in which the pulley shaft 1 is heated by the induction heating coil 7 to perform the carburizing process. It is a time chart figure. As shown in FIG. 8, the carburization control unit 6b controls the heating of the pulley shaft 1 to the predetermined temperature T by the induction heating coil 7 and raises the temperature rising state for a predetermined time after the temperature increase. [T (sec)] Continued control is performed. Then, the carburizing process is performed while rotating the pulley shaft 1 around the center line C.

FIG. 9 is a diagram for explaining the induction hardening process (conventional example). The induction hardening process is a process in which a part of the pulley shaft (for example, the surface of the pulley part) is heated for a short time and rapidly cooled as shown in FIG. 9, and is completely different from the carburizing process of the present invention. Different.
Then, according to the carburizing process shown in FIG. 8, a high surface pressure acts on the surface 4 (sliding surface of the belt) of the pulley portion 3 of the pulley shaft 1, but this surface pressure can be resisted. . Furthermore, although a load repeatedly acts on the pulley shaft 1, it can withstand this load and can extend the fatigue life.

Further, since the pulley shaft 1 has an effective hardened layer depth of 0.7 mm, for example, in FIG. 8, when the predetermined temperature T is 1150 ° C., the predetermined time t can be 540 seconds, When the predetermined temperature T is 1250 ° C., the predetermined time t is set to 396 seconds, and when the predetermined temperature T is 1300 ° C., the predetermined time t is set to 360 seconds. The predetermined temperature T can be set to 950 to 1350 ° C., and the predetermined time can be several seconds to several hours.

As described above, the second coil portion 20 is provided around the pulley portion 3 so as to extend from the front surface 4 to the back surface 5 of the pulley portion 3, so that the second coil portion 20 is illustrated in the example of FIG. As shown, both the front surface 4 and the back surface 5 of the pulley portion 3 can be heated and carburized. In addition, according to the structure of the induction heating coil 7 shown in FIG. 1, as shown to Fig.10 (a), the front opposing line part 25 (21) and back opposing line part 26 (22) of the 2nd coil part 20 are shown. ) And the direction of current flow is opposite.
And the edge part of the pulley part 3 is thin. Therefore, as shown in FIG. 10B, when the penetration depth of the eddy current generated by the induction heating coil 7 is large, the pulley portion 3 is heated from the surface 4 in the thin portion 3a. The eddy current generated on the front surface 4 side and the eddy current generated on the back surface 5 side for heating from the back surface 5 cancel each other, and the amount of generated heat is reduced. As a result, the expected effective hardened layer depth May not be obtained.
Specifically, the thickness B of the thin portion 3a is about 3 mm. In this case, for example, when the frequency is 25 kHz, eddy currents are canceled out in the region indicated by the cross hatch in FIG. As a result, an unheated portion is generated near the front surface 3 and the back surface 5. 10A and 10B, the front facing line portion 25 and the back facing line portion 26 are shown in a circular cross section for simplification.

Therefore, the frequency of the alternating current applied to the induction heating coil 7 by the power source 8 included in the control device 6 of the present invention is set to a high frequency (for example, 100 kHz).
Here, the penetration depth of the eddy current by the induction heating coil 7 will be described. The penetration depth δ is expressed by Expression (1). Note that f: frequency, μ: electrical conductivity (1 / Ωm), and σ: permeability (H / mm).
δ = 1 / (π × f × μ × σ) ^1/2 (1)

Therefore, the penetration depth δ of the eddy current can be made shallow by setting the frequency of the alternating current applied to the induction heating coil 7 high. Therefore, by setting the high frequency, as shown in FIG. 10A, the penetration depth δ of the eddy current can be made shallow especially on the front surface 4 and the back surface 5 of the thin portion 3a. The eddy current generated on the front surface 4 side and the eddy current generated on the back surface 5 side do not cancel each other. Therefore, the carburizing process can also be performed on the edge portion of the pulley portion 3.

FIG. 11 is an explanatory view showing an outline of another embodiment of the carburizing apparatus provided with the induction heating coil 7 of the present invention. In this embodiment, the shape of the whole winding part 27 which the 2nd coil part 20 of the induction heating coil 7 has differs compared with FIG. Others are the same. In the embodiment shown in FIG. 11, the connection position between the whole winding part 27 and the input line part 31 is different from that in the embodiment of FIG. 1. That is, in FIG. 1, there are three windings, but in FIG. 11, two windings and half.

FIG. 12 is a cross-sectional view of the edge of the pulley portion 3 and the entire winding portion 27 when the induction heating coil 7 of FIG. 11 is used. In FIG. 12, the entire winding portion 27 has a symmetrical structure in which the linear portion 25a of the front opposing line portion 25 and the linear portion 26a of the back opposing line portion 26 are symmetrically arranged on the front and back sides. The portion 28 (the portion surrounded by the two-dot chain line), the straight portion 25a of the front facing line portion 25, and the straight portion 26a of the back facing line portion 26 are asymmetrically arranged on the front and back sides. And an asymmetric structure portion 29 (a portion surrounded by a one-dot chain line).

That is, in the asymmetric structure 29, one of the winding on the front surface 4 side and the winding on the back surface 5 side that opposes the portion on the outermost peripheral side of the pulley portion 3 is omitted. In FIG. 12, the linear portion 26a on the back surface 5 side is omitted.
According to this configuration, it is possible to heat and carburize both the front surface 4 and the back surface 5 in the portion where the pulley portion 3 is thick, but the portion where the pulley portion 3 is thin. In 3a, as described above, eddy currents generated on the front surface 4 and the back surface 5 may cancel each other out and the heat generation amount may be reduced. However, the asymmetric structure portion 29 is a portion in which the front-facing line portion 25 and the back-facing line portion 26 are arranged asymmetrically on the front and back sides, so that one of the front surface 4 and the back surface 5 of the thin portion 3a The penetration depth δ of eddy current can be made shallower. For this reason, in the thin part 3a, it is possible to prevent the eddy currents generated on the front surface 4 and the back surface 5 from canceling each other, and to prevent an unheated portion from occurring near the front surface 3 and the back surface 5. can do. Therefore, the carburizing process can be performed also on the edge portion of the pulley portion 3. In the case of this embodiment, the frequency can be made lower than that of the above embodiment, for example, 25 kHz.

In the present invention, the winding of the induction heating coil 7 has a flat cross section (rectangular shape), and the surface area facing the surface of the pulley portion 3 of the pulley shaft 1 is larger than the winding having a circular cross section. Thereby, even if the pitch width of a winding becomes large, it can prevent that the amount of heating runs short.
In particular, as shown in FIG. 12, in the asymmetric structure portion 29, the linear portion 25a of the front facing line portion 25 has a flat cross section, thereby increasing the surface area facing the surface 4 and heating. Insufficient quantity is controlled.

According to each of the above embodiments, the first coil portion 10 of the induction heating coil 7 heats the shaft portion 2 of the pulley shaft 1 and the extending portion 3b, and the second coil portion 20 extends the extension of the pulley portion 3. Since the portions other than the portion 3b are heated, the pulley shaft 1 can be carburized by uniformly heating and holding the pulley shaft 1 for a predetermined time in a wide range. In particular, since the second coil portion 20 is wound around the pulley portion 3 from the front surface 4 to the back surface 5 of the pulley portion 3, both the front surface 4 and the back surface 5 of the pulley portion 3 are carburized. It becomes possible to process.
Furthermore, the 1st coil part 10 and the 2nd coil part 20 are the same cross-sectional areas, and are the same wire materials, and are integrated by serial arrangement | positioning. For this reason, the electric current which flows into the 1st coil part 10 and the 2nd coil part 20 becomes the same. Since the pulley portion 3 has a larger specific surface area than the shaft portion 2, the amount of heat radiation is large, and a large amount of energy is required to maintain the temperature after the temperature rise, but the second coil portion 20 satisfies this requirement. The necessary energy is effectively supplied, and the number of windings of the induction heating coil 7 is relatively set in the pulley unit 3. And the winding of the induction heating coil 7 is arrange | positioned so that the whole pulley shaft 1 can be heated uniformly.

Moreover, in the pulley part 3, the winding is arrange | positioned so that the surface 4 and the back surface 5 may be opposed. That is, the coil winding direction in the second coil part 20 (longitudinal direction of the winding facing the front surface 4 and the back surface 5) is a direction parallel to the Y axis, and the direction in which the surface of the pulley part 3 spreads. Since it is the same, the 2nd coil part 20 becomes the winding method which generates an eddy current efficiently in the surface 4 and the back surface 5. FIG.
Moreover, as shown in FIGS. 6 and 7, the pulley portion 3 has a shape in which the thickness gradually decreases toward the radially outer side. Therefore, in order to correspond to such a shape, each of the plurality of (three windings in the illustrated example) all winding portions 27 in the second coil portion 20 is radially outward (positive direction in the X-axis direction). In addition to being arranged at a predetermined pitch, they are arranged so that the distance between the front facing line portion 25 and the back facing line portion 26 facing each other becomes narrower toward the outside in the radial direction. With this configuration, it is possible to prevent the distance in the Z-axis direction between the pulley portion 3 and the entire winding portion 27 (the front-facing line portion 25 and the back-facing line portion 26) from separating toward the radially outer side. As a result, it becomes possible to uniformly heat the pulley portion 3 whose thickness gradually decreases toward the radially outer side.

Further, in this way, the pulley shaft 1 can be heated in a wide range for carburizing treatment, and the first coil portion 10 and the second coil portion 20 are integrated in series. The power supply 8 of the first coil part 10 and the second coil part 20 for heating the pulley part 3 and the shaft part 2 can be shared. For this reason, the structure of the carburizing apparatus can be simplified, and the cost of the apparatus can be reduced.

Further, the present invention is not limited to the illustrated form, and may be other forms within the scope of the present invention. In the said embodiment, although the workpiece | work to carburize was demonstrated as the pulley shaft 1 for CVT, another thing may be sufficient.

Claims

An induction heating coil for carburizing a pulley shaft having a disk-like pulley portion and a shaft portion on the same center line,
A first coil part for induction heating at least the shaft part;
A second coil portion provided around the pulley portion across the back surface from the front surface of the pulley portion for inductively heating the pulley portion;
With
The induction heating coil for carburizing treatment, wherein the first coil part and the second coil part are integrated in series.
The first coil portion extends in a direction parallel to the shaft portion and connects a pair of axial line portions arranged with the shaft portion interposed therebetween, and an axial line portion forming the pair. 2. The induction heating coil for carburizing treatment according to claim 1, further comprising: a detour portion that curves around the center line side and opens an end surface of the shaft portion in an axial direction.
The induction for carburizing treatment according to claim 1 or 2, wherein a space in which the pulley shaft can be taken in and out is formed from the first coil portion and the second coil portion in a direction perpendicular to the center line. Heating coil.
The second coil portion has a front facing line portion facing the front surface of the pulley portion and a back facing line portion facing the back surface, and the front facing line portion and the back facing line portion are asymmetric on the front and back sides. The induction heating coil for carburizing treatment according to claim 1 or 2, wherein the induction heating coil has an asymmetric structure portion that is arranged as follows.
The second coil portion has a front facing line portion facing the front surface of the pulley portion and a back facing line portion facing the back surface, and the front facing line portion and the back facing line portion are asymmetric on the front and back sides. The induction heating coil for carburizing treatment according to claim 3, wherein the induction heating coil has an asymmetric structure portion that is arranged as follows.
The first coil portion is a portion for induction heating the shaft portion, and a portion for induction heating the extending portion extending from the shaft portion of the pulley portion to both sides in the direction perpendicular to the center line. The induction heating coil according to claim 1 or 2, wherein:
The portion for inductively heating the shaft portion and the portion for inductively heating the extension portion are arranged along a virtual plane including the center line and around the pulley shaft. Induction heating coil.
An induction heating coil for carburizing a pulley shaft having a disk-shaped pulley portion and a shaft portion on the same center line;
A controller for heating the pulley shaft by the induction heating coil to raise the temperature and controlling the temperature rising state to continue for a predetermined time after the temperature rise;
The induction heating coil includes a first coil part for induction heating at least the shaft part, and a first coil part provided around the pulley part across the front surface to the back surface of the pulley part for induction heating the pulley part. Two coil parts,
The carburizing apparatus, wherein the first coil part and the second coil part are integrated in series.
The control device applies a high-frequency current to the induction heating coil so that an eddy current generated on the front surface side of the pulley unit by the second coil unit and an eddy current generated on the back surface side do not cancel each other. The carburizing apparatus according to claim 8, comprising a power source.