JP4698240B2 - Induction heating coil of shaft member or cylindrical member - Google Patents

Description

The present invention relates to an induction heating coil that heats and quenches the surface of a stepped cylindrical member such as an inner race of a large bearing to the bottom of a steep groove at the base of the stepped portion. In addition, the present invention provides induction heating for heating and quenching a shaft member or a cylindrical member having a circumferential groove on the outer periphery, or a cylindrical member having a stepped hollow portion or a dead end blind hole on the inner diameter and having a large or small difference in thickness. It relates to the coil.

  When the outer periphery of a shaft member or a cylindrical member having a circumferential groove is induction-heated using a normal cylindrical coil, there is a problem that when the temperature does not rise up to the bottom of the groove portion and quenching is performed, the hardness cannot be obtained in the groove portion. is there.

  Further, in induction heating and quenching of a stepped shaft member or a cylindrical member, a coil having a complicated shape has been used for simultaneously heating and quenching the surface of the large and small diameter portions and both side surfaces of the large diameter portion. Further, there is a case where a stealing groove is provided at the base of the stepped portion and quenching is required up to the bottom of the stealing groove. However, there is a problem that the groove cannot be hardened because the temperature does not rise up to the bottom of the stolen groove even when heated by a normal heating coil.

In addition, when the outer periphery of a cylindrical member having a difference in thickness or a shaft member having a blind hole in the center is induction-heat-quenched using a normal cylindrical coil, the thick part of the cylindrical member or the hole of the shaft member The part with large heat capacity, such as no part, has a smaller heating depth than the part with small heat capacity, such as the part with small wall thickness or the hole of shaft material, and the quenching layer of this part becomes thin There is.
There are no known examples of inventions that solve these problems.

  Then, this invention aims at providing the induction heating coil which solved the said problem.

In order to achieve the above object, an induction heating coil for a shaft member or a cylindrical member of the present invention is a cylindrical conductor induction heating coil for heating the outer surface of a shaft member or a cylindrical member having a circumferential groove on the outer periphery . A circumferential protrusion corresponding to the circumferential groove of the heated member is provided on the inner periphery, and a notch groove is provided on the outer periphery of the cylindrical conductor corresponding to the back side of the circumferential protrusion, so that the shaft of the heated member or the cylindrical The surface and the groove are heated.

Further, the induction heating coil of the stepped shaft member or cylindrical member of the present invention is a pseudo Ω character in induction heating of the stepped shaft member or cylindrical member having a stealing groove at the root of the step portion of the large diameter portion and the small diameter portion at both ends. The mold head is opposed to the axial direction of the outer peripheral surface of the large-diameter portion of the stepped portion, both side portions are opposed to the axis along the both side surfaces of the large-diameter portion, and both feet are the outer peripheral surface of the small-diameter portion. Two pieces of pseudo Ω-type derivatives made of linear conductors facing each other in the axial direction are arranged in parallel across the large-diameter portion of the heated member, and the foot ends of the two pseudo Ω-type derivatives A circuit is formed by connecting together, a protrusion is provided at a corner corresponding to the stealing groove of the conductor, and a notch groove is provided in a portion corresponding to the back side of the conductor, and heating to the groove bottom of the stealing groove It is characterized by.
Here, the pseudo Ω type “both sides are opposed to the axis perpendicular to both sides along the both sides of the large diameter part” means that not only the direction perpendicular to the axis but also the side surface of the large diameter part is inclined. The direction along the inclination is also included.

The induction heating coil of the stepped shaft member or cylindrical member of the present invention is suitable for heating the race surface of the stepped inner race of the large bearing and the step stealing groove.

Moreover, the induction heating coil of the cylindrical member of the present invention corresponds to the thick part of the heated member in the cylindrical conductor type induction heating coil that heats the outer surface of the cylindrical member having a difference in thickness. A constriction is provided on the outer peripheral portion of the cylindrical conductor so that the thickness of the cylindrical conductor is thinner than the portion corresponding to the thin portion of the heated member, thereby obtaining a uniform heating layer over the entire length of the heated cylindrical member. It is characterized by this.

According to the induction heating coil of the shaft member or the cylindrical member of the present invention, it is possible to heat to the bottom of the groove portion such as a shaft member having a groove which is difficult with a conventional heating coil or a stepped member having a stealing groove in the step portion. . In particular, it is possible to quench the race surface of the stepped inner race of the large bearing that requires quenching to the bottom of the stepped root groove and the step stealing groove, thereby contributing to cost reduction. Moreover, since the full length surface of the cylindrical member having a difference in thickness can be uniformly heated, the application of induction heating is expanded.

[First Embodiment]
In the first embodiment, a shaft member (hereinafter referred to as a work W1) having a circumferential groove shown in FIG. 1 is induction-heated and quenched. FIG. 1A is a sectional view of a cylindrical heating coil of the present invention, and FIG. 1B is a sectional view of a conventional cylindrical heating coil. When quenching a workpiece having a circumferential groove as shown in the figure, a cylindrical coil 20 'as shown in FIG. However, in such a heating coil, the surface h is heated, but the groove portion m is not heated, and there is a problem that the bottom portion of the circumferential groove m cannot be quenched as indicated by a broken line in FIG.

  Therefore, in the present invention, as shown in FIG. 1A, a circumferential protrusion 21 is provided on the inner peripheral portion corresponding to the circumferential groove m of the workpiece W1 of the cylindrical coil 20, and a circumferential cut groove 22 is provided on the outer periphery on the back side. It is. As a result, the magnetic flux concentrates in the groove due to the skin effect of the high-frequency current and the proximity effect of the protruding portion. Therefore, by heating and quenching while rotating the workpiece using this coil, a broken line is shown in FIG. Thus, the bottom of the groove can be heated and quenched.

  Table 1 shows the result of heating and quenching the shaft member provided with the circumferential groove having a depth of 5 mm and a width of 6 mm in FIG. 1 using the present invention and a conventional coil. As shown in Table 1, in both the coil of the present invention and the conventional coil of the comparative example, a hardened layer having the same depth and hardness was obtained on the surface portion. However, at the groove bottom, when the conventional heating coil of the comparative example was used, the quenching layer depth was 2.5 mm, but the heating temperature was low and the troostite structure remained, and the quenching hardness was about HRC56. A hardened and hardened layer could not be obtained. On the other hand, in the coil of the present invention, a quenching layer depth of 3.5 to 3.6 mm is obtained even at the groove bottom, and the heating temperature reaches the quenching temperature to prevent the formation of a troostite structure and quenching hardness. A proper hardened and hardened layer of HRC60 was obtained.

[Second Embodiment]
The second embodiment relates to the heating of the stepped cylindrical member shown in FIG. 2 is a front view of the heating coil as seen from the cross-section of the inner race of the inner toothed bearing that is a stepped cylindrical member, FIG. 3 is a sectional view taken along line XX of FIG. 2 , and FIG. 4 is the shape and arrangement of the heating coil. It is a perspective view which shows a state. In addition, the inside of the circle | round | yen of FIG. 4 is the local enlarged view of the stolen groove part of Embodiment 3. FIG.

Heated inner race of the second embodiment (hereinafter referred to as the workpiece W2), as shown in the sectional view of FIG. 3, the inner diameter d with a small diameter portion at both ends to the diameter D2 and D3 of the large-diameter portion of the width T at the diameter D1 It is a ring body, and relates to a coil that heat-hardens the outer periphery D1a of the large-diameter portion, both side surfaces Fa and Fb, and the surfaces D2a and D3a of the small-diameter portions at both ends.

As shown in FIGS. 2 and 4 , the heating coil is formed by connecting the foot portions of two conductors whose front shape is a pseudo Ω shape. In this pseudo-Ω-shaped conductor, the pseudo-Ω-shaped head 3 is axially opposed to the outer peripheral surface D1a of the large-diameter portion of the workpiece, and both sides of the pseudo-Ω-shaped are both side surfaces Fa and Fb of the large-diameter portion of the workpiece. The leg portions 1 and 5 are made of linear conductors facing the outer peripheral surfaces D2a and D3a of the small diameter portions at both ends in the axial direction. Then, two of the pseudo Ω-shaped conductors are placed in parallel and straddle the large-diameter portion of the work, and both feet 1, 5 of one pseudo Ω-shaped conductor are connected to the other feet 1 ', 5'. The terminals 8 and 9 connected to the power supply are drawn out from one end of the other pseudo-Ω-shaped conductors 2 ′ and 3 ′. In addition, in order to prevent heating of the corners on the outer periphery of the large-diameter portion, the connecting portions of the conductors 2 and 3 and the conductors 3 and 4 are connected by arc conductors 2a and 4a (simple in FIG. 2 ) that escape from the corners. As a result, the current introduced from the terminal 8 is the terminal 8-arc conductor 2'a-conductor 2'-1'-6-1-2-arc conductor 2a-conductor 3-arc conductor 4a-4-5-7-5. '-4'-arc conductor 4'a-3'-arc conductor 2'a-flows to terminal 9 to form a circuit.

When the heating coil having the above configuration is disposed across the large diameter portion of the workpiece as shown in FIG. 4 and power is applied to the heating coil by a power source (not shown) while rotating the workpiece, the outer peripheral surface D1a of the large diameter portion. The large-diameter side surfaces Fa and Fb and the small-diameter outer peripheral surfaces D2a and D3a are heated and quenched after being heated. Thereby, the whole outer periphery of a stepped cylindrical member can be heat-hardened with one coil.

[Third Embodiment]
The workpiece and the coil shape of the third embodiment shown in FIG. The shape of the work W3 of the third embodiment is also substantially the same as that of the second embodiment, but differs in that stealing grooves Ra and Rb are provided at the roots of the large diameter portion and the small diameter portion, respectively. In addition to the heating of the outer peripheral surface of the second embodiment, heating and quenching are required up to the bottom of the stealing grooves Ra and Rb.

When heating the workpiece W3 having the stealing grooves Ra and Rb in the stepped portion of FIG. 5 , the entire surface can be heated and hardened even if heated using the heating coil of the second embodiment, but the stealing grooves Ra, Since the bottom of Rb is not heated and the temperature does not rise, there arises a problem that the quenching hardness of the groove bottom cannot be obtained. That is, when the absence of grooves steals the stepped portion of the stepped cylindrical member, or to steal the grooves are not heated may be a heating coil of the second embodiment, but the grooves stealing as in the third embodiment of FIG. 5 If Ra and Rb are provided and quenching is required up to the bottom of the stolen grooves Ra and Rb, the object cannot be achieved. Therefore, the third embodiment is intended to heat and quench to the bottom of the stolen groove.

The heating coil of the third embodiment of FIG. 5 is the same as the coil of FIG. 2 as a circuit configuration, but the projections 10 corresponding to the stealing grooves Ra and Rb at the corners of the connecting portions of the conductors 1 and 2 and 4 and 5, respectively. , 12 are provided. And the cut grooves 11 and 13 are provided in the back side of the protrusion of a coil, respectively. The shape and size of the protrusion and the cut groove are determined experimentally.

When the heating coil having the above configuration is disposed across the large diameter portion of the workpiece as shown in FIG. 4 and power is applied to the heating coil by a power source (not shown) while rotating the workpiece, the outer peripheral surface D1a of the large diameter portion. Along with both side faces Fa and Fb of the large diameter portion and outer peripheral surfaces D2a and D3a of the small diameter portion, the bottom is heated to the bottom of the stealing groove and is cooled to the bottom of the stolen groove by cooling after heating.

FIG 2 and FIG second embodiment of the 5 and using the coil of the third embodiment, the large diameter portion outer diameter D1 = 2,660mmφ the shape shown in FIG. 5, the small diameter outer diameter D2 = 2,600mmφ, small A comparative test was conducted by heating and quenching a workpiece having a part outer diameter D3 = 2,620 mmφ, a large diameter part width T = 53 mm, and a groove radius r = 4 mm of the stealing grooves Ra, Rb. The heating coil of the third embodiment has a coil projection height of 2 mm and a cut groove having a width of 1 mm and a depth of 4 mm.

  The workpiece was heat-quenched and then cut, and the quenching hardness and the hardened layer depth were measured at the cross-sectional position shown in FIG. The experimental results are shown in Table 2. Also in the case of the coil of the second embodiment, as shown in Table 2, the surface hardness of each part was about HRC59, and the quench hardening depth was about 7 mm. However, the temperature of the stealing grooves Ra and Rb did not rise, and the quenching layer was 2.0 to 2.5 mm, but the troostite remained, the quenching hardness was as low as HRC56 to 58, and the crystal grain size was out of specification. It was.

On the other hand, when the coil provided with the protrusions of the third embodiment is used, the temperature of the stealing groove also rises so that the hardened layer becomes complete martensite, and the hardening hardness is about HRC59, which is the same as the surface. The hardened layer depth was also 3.5 mm or more. FIG. 7 is a photograph showing the depth of the etched hardened layer. From this photograph, the hardened layer depth of the stolen groove is well recognized.

  That is, when there is no stealing groove in the step portion of the stepped cylindrical member, or when the stealing groove is not heated, the heating coil of the second embodiment is effective. On the other hand, it has been found that the heating coil of the third embodiment is effective when quenching to the bottom of the stealing grooves Ra and Rb with the circles and members having the stealing grooves Ra and Rb.

[Fourth Embodiment]
The fourth embodiment shown in FIG. 8. In the fourth embodiment, as shown in the figure, the shaft member W3 having the blind holes B drilled from both ends is heated and quenched. When such a shaft material having a difference in thickness is heated by a conventional cylindrical coil, a thickened portion without a central hole has a quench hardening depth shallower than a portion having holes on both sides due to a difference in heat capacity. In the present invention, a constriction 41 is provided on the back side of the heating surface at the position of the heating coil 40 corresponding to the thick central portion. Thereby, since the magnetic flux density of a constriction part becomes large, the uniform hardening hardening depth is obtained along the full length. Although FIG. 8 shows an example of a shaft member having a blind hole, the present invention can also be applied to a case where there is a variation in the wall thickness even in the case of a pipe member through which a hole passes.

  As described above, according to the induction heating coil of the shaft member or the cylindrical member of the embodiment of the present invention, even in the induction heating of the member having the groove, the protrusion is provided in the portion corresponding to the groove portion of the heating coil, and the back side thereof is provided. By providing the cut groove in the corresponding portion, the groove portion can be heated to the bottom in the same manner as the surface of the member.

  Also, in induction heating of a stepped shaft member with a stealing groove at the base of the step, the pseudo Ω-shaped head faces the large diameter part, both sides face both side surfaces of the large diameter part, and both feet Two pseudo Ω-type conductors, each of which has a linear body facing the small-diameter portion, are disposed across the large-diameter portion of the heated member, and the legs of the pseudo-Ω-type conductor are connected to each other to form a circuit. By using an induction heating coil in which a protrusion is provided in the part facing the stealing groove of the step and a notch groove is provided in the part corresponding to the back side, the stepped shaft member is heated while rotating, etc. Can be heat-hardened to the bottom of the steep groove at the base of the step.

  Thereby, in the case of the inner race with a step of a large-sized bearing, a race surface and a step part stealing groove can be heat-hardened. In addition, even in the induction heating coil of a cylindrical member having a difference in thickness, the entire length of the heated cylindrical member is uniform by providing a constriction on the back side portion of the heating surface corresponding to the large thickness portion of the heating coil. A heated layer can be obtained.

As described above, according to the heating coil of the present invention, it is possible to easily heat and harden the groove bottom of the member to be heated having a groove, so that it is possible to expand the range of induction heating and contribute to industrial development.

It is sectional drawing of the cylindrical heating coil of the shaft member which has the circumferential groove | channel of 1st Embodiment of this invention. It is sectional drawing of the induction heating coil and workpiece | work of 2nd Embodiment of this invention. It is XX arrow sectional drawing of FIG. It is a figure explaining arrangement | positioning of the induction heating coil of 2nd Embodiment of this invention. It is sectional drawing of the induction heating coil and workpiece | work of 3rd Embodiment of this invention. It is a figure which shows the measurement cross section of the test result of 3rd Embodiment of this invention. It is a figure which shows the hardening layer of the test result of 3rd Embodiment of this invention. It is sectional drawing of the induction heating coil and workpiece | work of 4th Embodiment of this invention.

Explanation of symbols

1, 2, 3, 4, 5, 6, 7 conductor, 8, 9 lead portion, 10, 12 protrusion, 11, 13 notch, 20 cylindrical coil (cylindrical conductor) , 21 protrusion, 22 notch, 30 linear conductor coil, 31 projection, 32 notch, 40 cylindrical coil (cylindrical conductor) , 41 constriction, W1, W2 work (shaft member), W3 work (cylindrical member)

Claims (4)

In the cylindrical conductor type induction heating coil to heat the outer surface of the shaft member or cylindrical member having a circumferential groove on the outer periphery, circumferential projection provided corresponding to the circumferential groove of the heated member to the inner periphery of the cylindrical conductor, the An induction heating coil for a shaft member or a cylindrical member, wherein a notch groove is provided on the outer periphery of a cylindrical conductor corresponding to the back side of the circumferential protrusion , and the shaft or the surface of the heated member and the groove portion are heated. . In a cylindrical conductor type induction heating coil that heats the outer surface of a cylindrical member having a difference in thickness, the thickness of the cylindrical conductor corresponding to the thick portion of the heated member is the thickness of the heated member. An induction heating coil for a cylindrical member , wherein a constriction is provided on the outer peripheral portion of the cylindrical conductor so as to be thinner than a portion corresponding to a small portion of the cylindrical member, and a uniform heating layer is obtained over the entire length of the heated cylindrical member. In induction heating of a stepped shaft member or cylindrical member having a stealing groove at the root of the step portion of the large diameter portion and the small diameter portion at both ends, the pseudo Ω-shaped head is the shaft of the outer peripheral surface of the large diameter portion of the step portion A pseudo-Ω type derivative composed of linear conductors facing each other, with both sides facing each other in the direction perpendicular to the axis along both sides of the large diameter portion, and both feet facing the axial direction of the outer peripheral surface of the small diameter portion, Two pieces are arranged in parallel across the large-diameter portion of the heated member, and the foot ends of the two pseudo Ω-type derivatives are connected to form a circuit, and in the stealing groove of the conductor An induction heating coil for a stepped shaft member or a cylindrical member, wherein a protrusion is provided at a corresponding corner portion, and a notch groove is provided in a portion corresponding to the back side of the protrusion to heat the groove bottom of the stealing groove . The induction heating coil of a stepped cylindrical member according to claim 3 , wherein the stepped cylindrical member is a stepped inner race of a large bearing.

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