JP2001279320A - Induction heating coil and induction hardening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating coil used for restraining the deformation generated when induction hardening is applied to the upper part and the lower part of an inner wall surface of a long material. SOLUTION: The induction heating coil 20 is formed of linear upper conductor parts 22, 24 extended in the direction of arrow A and approaching only the upper parts 18a, 19a of the inner wall surfaces 18, 19 in the respective one pair of side walls 14, 16 in a steel-made member 10 and of linear lower conductor parts 26, 28 extended in the direction of arrow A and approaching only the lower parts 18b, 19b. The upper parts 18a, 19a of the inner wall surfaces 18, 19 are effectively heated with alternating magnetic flux generated with the upper conductor parts 22, 24 and also, the lower parts 18b, 19b of the inner wall surfaces 18, 19, are effectively heated with alternating magnetic flux generated with the lower conductor parts 26, 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating coil for heating an object to be heated and an induction hardening method for induction heating the object to be heated to a quenching temperature, quenching and hardening the object.

[0002]

2. Description of the Related Art Conventionally, there has been known an induction hardening method in which an object to be heated such as a steel member is heated to a quenching temperature and rapidly cooled by utilizing induction heating. There are various shapes of steel members, and when induction heating such steel members having various shapes, an induction heating coil corresponding to the shape of the steel member is usually used.

[0003] As one of the steel members, a bottom wall extending in a predetermined length direction, and a pair of side walls rising from both ends of the bottom wall in a width direction (a direction orthogonal to the length direction) and facing each other. In some cases, a long member having a substantially “U” -shaped cross section is used. Such a long material may be used, for example, after the inner wall surfaces of a pair of side walls are hardened.
In addition, this long material is often cut into a predetermined length (made into a fixed length material) and incorporated into an apparatus or the like. As described above, in order to fix the fixed length member with a bolt by incorporating the fixed length member into the apparatus, a bolt hole may be previously formed in the bottom wall of the long length member.

By the way, when the inner wall surface of the side wall of the long material as described above is induction hardened, generally, the entire length of the long material is set to be higher at both ends in the longitudinal direction than at the center in the longitudinal direction. The bow may be deformed (reversed). Such deformation becomes more noticeable as the length of the long material increases. Therefore, before quenching the inner wall surface of the side wall of the long material (for example, 5.0 m), the long material is cut into a fixed length (for example, 1.0 m), and the high frequency is separately set for each fixed length material. Quench.

[0005] However, even if the long material is cut into shorter material and quenched for each material, the deformation cannot be sufficiently suppressed. Then, a bolt is screwed into a bolt hole formed in the bottom wall of the fixed length material and fixed to a flat base, and the fixed length material is quenched in this state. Thereby, the deformation of the fixed-length material may be suppressed to an allowable amount or less.

[0006]

As described above, when quenching each fixed length material, bolts are tightened or loosened to fix or remove the fixed length material from the base.
To that extent, work is troublesome, and the work time is lengthened. Also, if the deformation of the standard length material cannot be suppressed below the allowable amount,
Work to correct this deformation is required.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides an induction heating coil used to suppress deformation during induction hardening of the upper and lower inner wall surfaces of a long material, and induction hardening using the induction heating coil. The aim is to provide a method.

[0008]

In order to achieve the above object, a first induction heating coil according to the present invention comprises a bottom wall extending in a predetermined length direction and rising from respective ends of the bottom wall in the width direction to mutually stand. In an induction heating coil for induction heating a long object to be heated having a pair of side walls facing each other when induction hardening is performed, (1) an induction heating coil which is close to only an upper part of an inner wall surface of each of the pair of side walls; A conductor portion; and (2) a lower conductor portion which is adjacent only to a lower portion of an inner wall surface of each of the pair of side walls. (3) The upper and lower portions are formed by an alternating magnetic flux generated by the upper conductor portion and the lower conductor portion. It is characterized in that only the lower portion is induction-heated.

Here, the above-mentioned induction heating coil comprises (4)
An upper / lower connecting conductor portion that connects the upper conductor portion and the lower conductor portion and is further distant from the inner wall surface than the upper conductor portion and the lower conductor portion may be provided.

According to a second induction heating coil of the present invention for achieving the above object, (5) a pair of power supply connection conductors each having one end connected to a high frequency power supply;
A pair of upper conductor portions extending parallel to each other at a predetermined interval,
(7) a pair of lower conductors extending parallel to each other at a predetermined distance below the upper conductors, (8)
An upper and lower connection conductor located between the pair of upper conductors and between the lower conductors, connecting one end on the same side of both the pair of upper conductors and the pair of lower conductors. (9) a pair of first connection conductors for connecting the other end of the pair of lower conductors opposite to the one end to the pair of power supply connections, respectively; And a second connecting conductor connecting the other ends of the upper conductor opposite to the one end.

Here, (11) the first connection conductor portion is
It may be located between the pair of lower conductors.

According to another aspect of the present invention, there is provided an induction hardening method comprising: a bottom wall extending in a predetermined length direction; and a pair of side walls rising from respective widthwise ends of the bottom wall and facing each other. In the induction quenching method for induction hardening a long object to be heated, (12) only the upper and lower portions of the inner wall surfaces of the pair of side walls are heated to the quenching temperature, and (13) the quenching temperature is heated. The quenched portion is rapidly cooled and hardened.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view schematically showing a first embodiment of an induction heating coil according to the present invention, wherein an arrow represents an example of a current, and a two-dot chain line represents an object to be heated. FIG. 2 shows FIG.
FIG. 2 is a front view schematically showing a state in which an object to be heated is induction-heated using the induction heating coil of FIG. FIG. 3 schematically shows a method of measuring the warpage, (a) is a front view,
(B) is a side view. FIG. 4 is a graph showing the measurement results of the warpage. FIG. 5 is a graph showing the results of the hardness measurement.

The induction heating coil 20 is made of copper, and is used for induction heating of a steel member 10 having a substantially "U" -shaped cross section as shown in FIG. It is used for The portion of the steel member 10 to be induction-heated is the inner wall surface 1 of each of the pair of side walls 14 and 16.
8 and 19 at the top and bottom.

The steel member 10 includes a bottom wall 12 extending in a direction of an arrow A (an example of a predetermined length direction in the present invention),
The bottom wall 12 has a pair of side walls 14 and 16 rising from both ends in the width direction (the direction of the arrow B perpendicular to the direction of the arrow A) and facing each other. Induction heating coil 20
Has a shape substantially symmetrical with respect to a line segment extending in the direction of arrow A at the center in the width direction of the bottom wall 12. Induction heating coil 20
While moving from one end to the other end in the longitudinal direction of the steel member 10 (moving in the direction of arrow A), the upper portions 18a, 19a and the lower portions 18b, 19b of the inner wall surfaces 18, 19 are moved.
Is induction heated to the quenching temperature.

The induction heating coil 20 has a linear upper conductor portion 22 extending in the direction of arrow A only in proximity to the upper portions 18a, 19a of the inner wall surfaces 18, 19 of the pair of side walls 14, 16 of the steel member 10, respectively. 24, and linear lower conductor portions 26, 2 extending in the direction of arrow A only in the vicinity of lower portions 18b, 19b.
8 is provided. The upper portions 18a and 19a of the inner wall surfaces 18 and 19 are efficiently heated by the alternating magnetic flux generated by the upper conductor portions 22 and 24, and the inner magnetic walls 18 and 19 are formed by the alternating magnetic flux generated by the lower conductor portions 26 and 28. Lower part 18b,
19b is efficiently heated. In addition, the upper conductor parts 22 and 2
Numeral 4 extends parallel to each other at a predetermined interval, and lower conductors 26 and 28 extend below the upper conductors 22 and 24 at a predetermined interval and parallel to each other. Here, the predetermined interval refers to an interval slightly shorter than the interval between the pair of inner wall surfaces 18 and 19. A core (not shown) is sandwiched between the upper conductor portion 22 and the lower conductor portion 26, and a core (a magnetic material, not shown) is also provided between the upper conductor portion 24 and the lower conductor portion 28. ) Is sandwiched. This core weakens the alternating magnetic flux penetrating portions other than the upper portions 18a and 19a and the lower portions 18b and 19b.

One end of the upper conductor portion 22 and the lower conductor portion 26 on the side opposite to the direction of the arrow A is connected in an up-down manner in such a manner that the U-shape is turned sideways and the opening faces the inner wall surface 18. They are connected by a conductor 30. Similarly, one end of the upper conductor portion 24 and the lower conductor portion 28 on the side opposite to the direction of arrow A has an upper and lower connection conductor portion having a shape in which the U-shape is turned sideways and the opening faces the inner wall surface 19. 32. These upper and lower connection conductor portions 30 and 32 are separated from the inner wall surfaces 18 and 19. For this reason, the inner wall surfaces 18 and 19 are hardly heated by the alternating magnetic flux generated by the upper and lower connection conductor portions 30 and 32.

At the other end of the lower conductor 26 opposite to the one end, a first connection conductor 34 extending in a direction perpendicular to both the arrow A direction and the arrow B direction and extending away from the bottom wall 12 is provided.
Are connected continuously. Similarly, the other end of the lower conductor 28 opposite to the one end is provided with an arrow A direction and an arrow B
The first connection conductors 36 which are orthogonal to both directions and extend in a direction away from the bottom wall 12 are continuously connected. The first connection conductors 34 and 36 are respectively connected to the inner wall surface 1.
It extends substantially parallel to and near 8,19. However, since the induction heating coil 10 moves in the direction of arrow A, the inner wall surfaces 18 and 19 are not heated much by the alternating magnetic flux generated by the first connection conductors 34 and 36.

Power supply connection conductors 38, 40 are continuously connected from the upper ends of the first connection conductors 34, 36, respectively. One end of each of the power supply connection conductors 38 and 40 is connected to a high frequency power supply 50. The power supply connection conductors 38 and 40 are separated from the inner wall surfaces 18 and 19. Therefore, the inner wall surfaces 18, 19 are hardly heated by the alternating magnetic flux generated by the power supply connection conductors 38, 40.

The other ends of the upper conductors 22 and 24 on the side opposite to the one end are connected by a second connection conductor 42. The second connecting conductor portion 42 has a shape in which the U-shape is widened and inverted, and the inner wall surfaces 18 and 19 are hardly heated by the alternating magnetic flux generated by the second connecting conductor portion 42.

In induction hardening the inner wall surfaces 18 and 19 of the steel member 10 using the above-described induction heating coil 20, first, the induction heating coil 20 is moved from one end to the other end in the longitudinal direction of the steel member 10. (Arrow A
The inner wall surfaces 18 and 19 are induction-heated. In this case, the upper conductor portion 2 of the induction heating coil 20
Due to the alternating magnetic flux generated in the lower and upper conductor portions 26, 28, only the surface layers of both the upper portions 18a, 19a and the lower portions 18b, 19b of the inner wall surfaces 18, 19 are heated to a quenching temperature higher than the austenite transformation point. .

A cooling jacket (not shown) for jetting a cooling liquid is integrally fixed to the induction heating coil 20 on the upstream side in the moving direction of the induction heating coil 20 (here, the direction of arrow A). . Therefore, the portion of the steel member 10 heated to the quenching temperature by the induction heating coil 20 (only the upper portions 18a and 19a and the lower portions 18b and 19b of the inner wall surfaces 18 and 19) is efficiently cooled and transformed into martensite. And cure.

Due to the martensitic transformation, upper portions 18a, 19a and lower portions 18b, 1 of inner wall surfaces 18, 19 are formed.
9b hardens and expands, trying to bow the steel member 10 in an arc. However, the intermediate portion between the inner wall surfaces 18 and 19 does not expand without being hardened. As a result, the steel member 10 hardly warps or bends.

Referring to FIGS. 3 and 4, the result of the experiment for measuring the above-described warpage will be described.

The length L of the steel member 10 used in this experiment is 2
The height H of the side walls 14 and 16 is about 50 mm, the width W inside the bottom wall 12 is about 60 mm, and the material is JIS.
And the one equivalent to S53C was used. Prior to the measurement of the warp, the steel member 10 is induction hardened using the above-described induction heating coil 20 or the like, and the upper portions 18a, 19a and the lower portions 18b, 19 of the inner wall surfaces 18, 19 of the side walls 14, 16 are formed.
A cured layer was formed on b. The hardness distribution of the cured layer will be described later with reference to FIG. The inner wall surfaces 18, 19
The conditions for induction heating the upper portions 18a and 19a and the lower portions 18b and 19b to the quenching temperature are as follows: voltage 360V, frequency 50k
Hz, the high-frequency power 75 kW, and the moving speed of the induction heating coil 20 were 2.0 mm / sec.

In measuring the warpage of the steel member 10, the steel member 10 is fixed on the fixing base 6 so that the bottom wall 12 faces upward.
0, and the warpage was measured while the dial gauge 62 was in contact with the lower surface 12 a of the bottom wall 12. Here, L1 shown in FIG. 3B is 300 mm, L2 is also 300 mm,
L3 is also 300 mm, L8 is also 300 mm, L9 is 10
0 mm.

300 m from one end in the direction of arrow A shown in FIG.
The deflection of the dial gauge 62 was measured with the position of m as a reference point (0). When the dial gauge 62 sways to the + side, the warp is such that both ends in the longitudinal direction of the steel member 10 are higher than the central portion in the longitudinal direction. And warpage in the opposite direction. FIG. 4 shows a graph of the measurement result of the warpage. The curve shown by the square in FIG. 4 is a result of the conventional method in which the entire inner wall surfaces of the side walls 14 and 16 are hardened. On the other hand, the circular curve (substantially straight line) shown in FIG.
9 is a result of the method of the present invention in which only the surface layers of both the upper portions 18a and 19a and the lower portions 18b and 19b of No. 9 are cured.

As shown in FIG. 4, in the conventional method, a steel member 1 is used.
While a large warp occurred at 0, the warp hardly occurred in the method of the present invention. As described above, the upper portions 18a, 19 of the inner wall surfaces 18, 19 of the side walls 14, 16 of the steel member 10 are formed.
It has been found that by hardening only the surface layers of both a and the lower portions 18b and 19b, the warpage of the steel member 10 can be suppressed. Therefore, when the object to be heated 10 is long, the object to be heated 10 whose warpage is suppressed can be obtained even if induction hardening is performed without cutting the object to be short.

FIG. 5 shows upper and lower portions 18a, 19a and 18a of inner wall surfaces 18, 19 of the side walls 14, 16 of the steel member 10.
b, 19b and an example of the hardness distribution of the intermediate portions 18c, 19c. The horizontal axis in FIG. 5 represents the distance from the surface of the inner wall surface, and the vertical axis represents the hardness.

As shown in FIG. 5, a sufficient hardness distribution was obtained at the upper portions 18a, 19a and the lower portions 18b, 19b of the inner wall surfaces 18, 19. On the other hand, the intermediate portions 18c, 19
c is hardly cured. Therefore, the intermediate portions 18c,
A hole or the like can be easily formed in 19c. [Second Embodiment] FIG. 6 is a perspective view schematically showing a second embodiment of the induction heating coil of the present invention, and arrows represent an example of a current. 6, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

The feature of the induction heating coil 70 of the second embodiment is that the first conductor 26 connects the lower conductor 26 to the power supply conductor 38.
The point where the connection conductor 72 is located inside the inner wall 18 away from the inner wall surface 18 (see FIG. 1) and the first connection conductor 74 that connects the lower conductor 28 to the power supply connection conductor 40 are the inner wall 19 (see FIG. 1). 1
(See reference).

By separating the first connection conductors 72 and 74 from the inner wall surfaces 18 and 19 in this manner, the inner wall surfaces 18 and 19 are more difficult to be heated by the first connection conductors 72 and 74. As a result, the intermediate portions 18c and 19c of the inner wall surfaces 18 and 19 are harder to harden. Therefore, holes and the like can be more easily formed in the intermediate portions 18c and 19c.

[0034]

As described above, according to the first induction heating coil of the present invention, only the upper and lower portions of the inner wall surface of the side wall are heated, and the intermediate portion between the upper and lower portions is not heated.
Therefore, when the upper and lower portions of the inner wall surface are heated to the quenching temperature and rapidly cooled, only the upper and lower portions of the inner wall surface are hardened, and the intermediate portion is not hardened. As a result, when a hole is formed in the intermediate portion, the hole can be easily formed. Further, since the hardened layer is not formed in the intermediate portion, the total volume of the hardened layer is smaller than when the hardened layer is also formed in the intermediate portion. As a result, deformation of the whole object to be heated is reduced as compared with the case where the cured layer is also formed in the intermediate portion. When the object to be heated is heated to the quenching temperature and quenched by using the induction heating coil of the present invention, the deformation of the object to be heated is reduced, so that the correction of the object to be heated may be omitted.

Here, when the above-mentioned induction heating coil has upper and lower connecting conductors for connecting the upper and lower conductors, the upper and lower connecting conductors being further away from the inner wall surface than the upper and lower conductors are. Since the upper and lower connection conductors are separated from the inner wall surface, the inner wall surface is not heated much by the alternating magnetic flux generated in the upper and lower connection conductor portions. For this reason, the deformation of the object to be heated is further reduced.

In addition, using the second induction heating coil of the present invention, a long wall having a bottom wall extending in a predetermined length direction and a pair of side walls rising from both ends in the width direction of the bottom wall and facing each other. When the object to be heated is induction hardened, the pair of upper conductors each approach the upper portion of the inner wall surface of the pair of side walls, and the pair of lower conductor portions each approach the lower portion of the inner wall surface of the pair of side walls. Can be. In this case, since the upper and lower connecting conductors are located inside the pair of upper and lower conductors, they are separated from the inner wall surface. Therefore, only the upper and lower portions of the inner wall surface are heated, and the intermediate portion between the upper and lower portions is not heated. Therefore, when the upper and lower portions of the inner wall surface are heated to the quenching temperature and rapidly cooled, only the upper and lower portions of the inner wall surface are hardened, and the intermediate portion is not hardened. As a result, when a hole is formed in the intermediate portion, the hole can be easily formed. Further, since the hardened layer is not formed in the intermediate portion, the total volume of the hardened layer is smaller than when the hardened layer is also formed in the intermediate portion. As a result, deformation of the whole object to be heated is reduced as compared with the case where the cured layer is also formed in the intermediate portion. When the object to be heated is heated to the quenching temperature and quenched by using the induction heating coil of the present invention, the deformation of the object to be heated is reduced, so that the correction of the object to be heated may be omitted.

Here, if the first connection conductor is located between the pair of lower conductors, the first connection conductor is also separated from the inner wall surface, so that the intermediate portion of the inner wall surface is further increased. Hard to heat. As a result, the deformation of the object to be heated is further reduced.

According to the induction hardening method of the present invention,
Only the upper and lower portions of the inner wall surface of the side wall are hardened, and the intermediate portion between the upper and lower portions is not hardened. As a result, when a hole is formed in the intermediate portion, the hole can be easily formed. Further, since the hardened layer is not formed in the intermediate portion, the total volume of the hardened layer is smaller than when the hardened layer is also formed in the intermediate portion. As a result, deformation of the whole object to be heated is reduced as compared with the case where the cured layer is also formed in the intermediate portion. As described above, in the induction hardening method of the present invention, since the deformation of the object to be heated is reduced, the correction of the object to be heated may be omitted.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of an induction heating coil of the present invention.

FIG. 2 is a front view schematically showing a state where an object to be heated is induction-heated using the induction heating coil of FIG. 1;

FIGS. 3A and 3B schematically show a method for measuring warpage, FIG. 3A is a front view, and FIG. 3B is a side view.

FIG. 4 is a graph showing measurement results of warpage.

FIG. 5 is a graph showing the results of hardness measurement.

FIG. 6 is a perspective view schematically showing a second embodiment of the induction heating coil of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Steel member 12 Bottom wall 14, 16 A pair of side walls 18, 19 Inner wall surface 18a, 19a Upper part of inner wall surface 18b, 19b Lower part of inner wall surface 18c, 19c Intermediate part of inner wall surface 20, 70 Induction heating coil 22, 24 Top Conductor 26, 28 Lower conductor 30, 32 Upper and lower connection conductor 34, 36, 72, 74 First connection conductor 38, 40 Power supply connection conductor 50 High frequency power supply

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 6/36 H05B 6/36 D (72) Inventor Toshiyuki Kaneko Yamanoi Industrial Park, Sanyo-cho, Asa-gun, Yamaguchi Pref. Inside Netulen Heat Treat (72) Inventor Satoru Satori Satoru Sakai Yamanoi Industrial Park, Sanyo-cho, Asa-gun, Yamaguchi Pref. F-term (for reference) 3K059 AA09 AB22 AD34 CD52

Claims (5)

[Claims] When a long object to be heated is induction hardened having a bottom wall extending in a predetermined length direction and a pair of side walls rising from respective ends in the width direction of the bottom wall and facing each other, the object is heated. An induction heating coil for induction heating an object, comprising: an upper conductor portion that is adjacent only to an upper portion of an inner wall surface of each of the pair of side walls; and a lower conductor portion that is only adjacent to a lower portion of an inner wall surface of each of the pair of side walls. An induction heating coil, wherein only the upper part and the lower part are induction-heated by an alternating magnetic flux generated in the upper conductor part and the lower conductor part. 2. The semiconductor device according to claim 1, further comprising upper and lower connection conductors for connecting the upper conductor and the lower conductor, the upper and lower connection conductors being further away from the inner wall surface than the upper conductor and the lower conductor. 4. The induction heating coil according to claim 1. 3. A pair of power supply connection conductors each having one end connected to a high-frequency power supply; a pair of upper conductors extending in parallel with each other at a predetermined interval; A pair of lower conductors extending in parallel with each other at a predetermined distance; and a pair of upper conductors connecting one end on the same side of both the pair of upper conductors and the pair of lower conductors. Upper and lower connection conductor portions located between the lower conductor portions, and a pair of second connection portions respectively connecting the other end portions of the pair of lower conductor portions opposite to the one end portions to the pair of power supply connection portions. An induction heating coil, comprising: a first connection conductor; and a second connection conductor connecting the other ends of the pair of upper conductors opposite to the one end. 4. The induction heating coil according to claim 3, wherein the first connection conductor is located between the pair of lower conductors. 5. An induction hardening method for induction hardening a long object to be heated having a bottom wall extending in a predetermined length direction and a pair of side walls rising from respective ends of the bottom wall in the width direction and facing each other. An induction quenching method, wherein only the upper and lower portions of the inner wall surfaces of the pair of side walls are heated to the quenching temperature, and the portions heated to the quenching temperature are rapidly cooled and hardened.