JP2005060799A - Induction hardening equipment and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide induction hardening equipment which performs quenching of a groove wall on a cylindrical member such as a hub outer ring with a groove formed on its inner periphery, according to a plan without causing quenching crack. <P>SOLUTION: A copper shield member 94 is removably fixed inside a cup-shaped upper center 90 with a bolt 95 etc. The copper shield member 94 has a disk shape and has a thickness almost equal to the distance between the bottom of the cup-shaped upper center 90 to the top of a thin-walled part 38. A rim 94a of the shield member 94 projects downward, faces the inner periphery of about one-third of the upper portion of the thin-walled part 38 and contacts the thin-walled part 38. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an induction hardening apparatus and an induction hardening method for hardening a wall surface of a groove formed on an inner peripheral surface of a side wall of a cylindrical member.

  Hub outer rings and hub inner rings are widely used as parts of vehicles. For example, two grooves are formed on the inner peripheral surface of the side wall of the hub outer ring. These two grooves extend in the circumferential direction and are separated by a predetermined distance in the height direction of the hub outer ring. Since a load acts on the wall surfaces of the two grooves, a hardened layer is generally formed on the wall surfaces of the two grooves. A technique for forming a hardened layer on the wall surfaces of two grooves will be described with reference to FIG.

  FIG. 6 is a schematic diagram showing a conventional induction hardening method for forming a hardened layer on the wall surfaces of two grooves.

  The hub outer ring 10 is cylindrical, and two grooves 16 and 18 are formed on the inner peripheral surface 14 of the side wall 12. In order to form the hardened layers 16b and 18b on the wall surfaces 16a and 18a of the grooves 16 and 18, the induction heating coil 20 is arranged facing the wall surfaces 16a and 18a of the grooves 16 and 18, and this induction heating coil 20 is formed. The wall surfaces 16a and 18a are heated to the quenching temperature through a high-frequency current and rapidly cooled. Thereby, the hardened layers 16b and 18b are formed on the wall surfaces 16a and 18a of the grooves 16 and 18, respectively. The depth of the hardened layers 16b and 18b is determined by design.

  By the way, there is the hub outer ring 10 in which the thickness t1 of the opposite side portion 12a opposite to the groove 18 across the groove 16 in the side wall 12 is thinner than the thickness t2 of the vicinity portion 12b of the groove 18. In the case of such a hub outer ring 10, when the hardened layer 18 b is designed to have a designed depth, the hardened layer 16 b becomes deeper due to the difference in thickness and shape between the thicknesses t 1 and t 2, and the cracks are cracked. May occur. On the other hand, when the hardened layer 16b has a designed depth, the hardened layer 18b becomes too shallow.

  Therefore, a technique is known in which the diameter of the portion 20 a facing the groove 16 in the induction heating coil 20 is made thinner than the portion 18 a facing the groove 18. A technique is also known in which induction heating is performed while injecting a cooling liquid 22 onto the outer peripheral surface of the side wall 12 opposite to the groove 16.

  Among the techniques described above, in the technique of reducing the diameter of the induction heating coil 20, the depths of the two hardened layers 16b and 18b satisfy the design depth. However, the hardened layer 16b cannot be prevented from extending upward, and therefore, it may not be possible to prevent the occurrence of burning cracks.

  Further, in the technique of injecting the cooling liquid 22 to the outer peripheral surface of the side wall 12 opposite to the groove 16, the hardened layer 16 b can be prevented from extending upward, but when the cooling liquid is injected to the wall surface 16 a, There is a possibility that cracking may occur due to a stress difference between the inner peripheral surface and the outer peripheral surface.

  In view of the above circumstances, the present invention provides an induction hardening apparatus and induction hardening that harden a wall surface of a groove as designed without causing cracking in a cylindrical member such as a hub outer ring having a groove formed on an inner peripheral surface. It aims to provide a method.

The first induction hardening apparatus of the present invention for achieving the above object is to form a hardened layer on a wall surface of the groove among cylindrical members having grooves extending in the circumferential direction on the inner peripheral surface of the side wall. In the induction hardening device for
(1) an induction heating coil disposed facing the wall surface of the groove;
(2) It is characterized by comprising a shield member which is disposed facing the vicinity of the wall surface of the groove in the inner peripheral surface of the side wall of the cylindrical member and which is difficult to pass magnetic flux.

In addition, the second induction hardening apparatus of the present invention for achieving the above object is that the first groove and the second groove extending in the circumferential direction are spaced apart by a predetermined distance in the height direction on the inner peripheral surface of the side wall. The cylindrical member is formed such that the thickness of the opposite side portion of the side wall opposite to the second groove across the first groove is thinner than the thickness of the vicinity of the second groove. In the induction hardening apparatus for forming a hardened layer on the wall surfaces of the first and second grooves,
(3) an induction heating coil disposed to face the wall surfaces of the first and second grooves;
(4) A shield member that is arranged to face the inner peripheral surface of the opposite side portion of the side wall and hardly allows magnetic flux to pass therethrough is provided.

here,
(5) The shield member is made of a conductive and nonmagnetic material.

further,
(6) The shield member may be made of any material of copper, aluminum, silver, and nickel.

Furthermore,
(7) The shield member may be disposed to face an adjacent portion adjacent to the wall surface of the first groove in the inner peripheral surface of the side wall.

Furthermore,
(8) The shield member may be disposed in contact with the inner peripheral surface.

Furthermore,
(9) The opposite side portion is formed in an annular shape,
(10) The shield member may be an annular member disposed along the inner peripheral surface of the opposite side portion.

Furthermore,
(11) A contact jig may be provided that surrounds and contacts the outer peripheral surface of the opposite side portion.

Furthermore,
(12) The shield member may be detachably fixed to the presser jig.

Further, in the induction hardening method of the present invention for achieving the above object, the first groove and the second groove extending in the circumferential direction are formed on the inner peripheral surface of the side wall at a predetermined interval in the height direction. The thickness of the opposite side portion of the side wall opposite to the second groove sandwiching the first groove is smaller than the thickness of the portion near the second groove, and the first and second cylindrical members are thin. In the induction hardening method for forming a hardened layer on the wall surface of the second groove,
(13) While arranging the induction heating coil facing the wall surfaces of the first and second grooves,
(14) A shield member that is difficult to pass magnetic flux is arranged facing the inner peripheral surface of the opposite side portion of the side wall,
(15) The induction heating coil is rapidly cooled by heating the wall surfaces of the first and second grooves to a predetermined quenching temperature through a high-frequency current.

here,
(16) When the wall surfaces of the first and second grooves are heated to a predetermined quenching temperature and rapidly cooled, the coolant may be sprayed onto the outer peripheral surface of the opposite side portion of the side wall.

  In the first induction hardening apparatus of the present invention, since the induction heating coil is disposed facing the wall surface of the groove, the wall surface is induction heated to the quenching temperature. However, since the shield member that hardly allows magnetic flux to pass is arranged in the vicinity of the wall surface of the groove on the inner peripheral surface of the side wall, the magnetic flux does not easily pass through this vicinity and is difficult to be induction heated. Therefore, since the vicinity of the wall surface of the groove is not inadvertently cured, cracks caused by induction hardening of the wall surface of the groove do not occur. Further, by appropriately adjusting the position where the shield member is disposed, it is difficult for the magnetic flux to pass through a part of the wall surface of the groove, and this part is less likely to be induction-heated. Can be shallow.

  Moreover, in the 2nd induction hardening apparatus of this invention, since the induction heating coil is arrange | positioned facing the wall surface of the 1st and 2nd groove | channel, these wall surfaces are induction-heated to quenching temperature. However, since shield members that do not allow magnetic flux to pass through are arranged facing each other on the inner peripheral surface of the opposite side portion of the side wall, it is difficult for magnetic flux to pass through the opposite side portion and it is difficult for induction heating. Accordingly, the opposite side portion of the wall surface of the first groove is not inadvertently hardened, so that cracks due to induction hardening of the wall surfaces of the first and second grooves do not occur. Further, by appropriately adjusting the position where the shield member is disposed, it is difficult for the magnetic flux to pass through a part of the wall surface of the first groove and the part is less likely to be induction-heated. The hardened layer can be made shallower.

  Moreover, in the induction hardening method of this invention, since the induction heating coil is arrange | positioned facing the wall surface of the 1st and 2nd groove | channel, these wall surfaces are induction-heated to quenching temperature. However, since shield members that do not allow magnetic flux to pass through are arranged facing each other on the inner peripheral surface of the opposite side portion of the side wall, it is difficult for magnetic flux to pass through the opposite side portion and it is difficult for induction heating. Accordingly, the opposite side portion of the wall surface of the first groove is not inadvertently hardened, so that cracks due to induction hardening of the wall surfaces of the first and second grooves do not occur. Further, by appropriately adjusting the position where the shield member is disposed, it is difficult for the magnetic flux to pass through a part of the wall surface of the first groove and the part is less likely to be induction-heated. The hardened layer can be made shallower.

  The present invention is realized, for example, when quenching a wall surface of a groove formed on an inner peripheral surface of a hub outer ring.

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

  An example of a cylindrical member to which the induction hardening method of the present invention is applied will be described with reference to FIGS.

  FIG. 1 is a perspective view showing a hub outer ring and an upper center as an example of a cylindrical member. FIG. 2 is a longitudinal sectional view of the hub outer ring, and also shows an induction heating coil inserted into the hub outer ring.

  The hub outer ring 30 has a cylindrical shape, and a disk-shaped flange 32 is formed at the bottom thereof. A bolt hole 32 a for fixing the hub outer ring 30 is formed in the flange 32. The hub outer ring 30 has a cylindrical side wall 34. As shown in FIG. 2, a portion 36 (referred to as a thick portion 36) of the side wall 34 from the bottom to about two thirds of the height direction is referred to as a portion 38 (a thin portion 38) above this portion. , Which is an example of the opposite portion in the present invention). Further, a step 42 is formed in the outer peripheral surface 40 of the side wall 34 at a position of about two thirds of the height direction from below, and the outer diameter of the thick portion 36 is larger than the outer diameter of the thin portion 38. Somewhat big. Of the inner peripheral surface 50 of the side wall 34, the inner diameter of the portion (the portion corresponding to the thick portion 36) from the bottom to about two-thirds in the height direction is higher than this portion (the thin portion 38). Smaller than the inner diameter of the portion corresponding to.

  An annular groove 52 (an example of the second groove according to the present invention) extending in the outer peripheral direction is formed at the center of the inner peripheral surface 50 in the height direction (arrow H direction) of the thick portion 36. . Further, an annular groove 54 (an example of the first groove according to the present invention) extending in the outer peripheral direction is formed at the boundary between the thick portion 36 and the thin portion 38 in the inner peripheral surface 50. The cross section of the groove 52 (the surface cut at right angles to the outer circumferential direction) is semicircular. The distance from the wall surface 52 a of the groove 52 to the outer peripheral surface 40 becomes shorter from the wall surface near the opening of the groove 52 toward the wall surface corresponding to the bottom surface of the groove 52.

  The cross section of the groove 54 (surface cut at right angles to the outer peripheral direction) is also semicircular, but is shallower than the groove 52. A lower portion (upstream portion in the arrow H direction) of the groove 54 is formed in the thick portion 36, and an upper portion (downstream portion in the arrow H direction) of the groove 54 is formed in the thin portion 38. For this reason, the upper part of the groove 54 is a very shallow groove. Further, the distance (wall thickness t2) from the wall surface 54b of the upper portion of the groove 54 to the outer peripheral surface 40 is shorter than the distance (wall thickness t1) from the wall surface 54a of the lower portion of the groove 54 to the outer peripheral surface 40. An annular convex portion 56 is formed at the upper end portion of the opening of the groove 54. An induction heating coil 70 for heating the wall surfaces of the grooves 52 and 54 is disposed in the hollow portion of the hub outer ring 30.

  With reference to FIG. 3 and FIG. 4, the induction hardening apparatus which forms a hardened layer in the wall surface of the groove | channels 52 and 54 of the hub outer ring | wheel 30 is demonstrated.

  FIG. 3 is a cross-sectional view showing the induction heating coil and the cup-type upper center disposed in the hollow portion of the hub outer ring. FIG. 4 is a perspective view schematically showing the direction of current passing through the induction heating coil at a certain moment.

  The induction hardening device 60 includes a disk-like mounting table 62 on which the hub outer ring 30 is mounted, and an induction heating coil 70 that is disposed in the hollow portion of the hub outer ring 30 and heats the wall surfaces of the grooves 52 and 54. ing. A large opening is formed in the central portion of the mounting table 62, and the induction heating coil 70 is configured to pass through this opening and reach the hollow portion of the hub outer ring 30. The mounting table 62 is configured to rotate at a predetermined number of revolutions, and the hub outer ring 30 is rotated with the rotation of the mounting table 62 while the induction heating coil 70 is heating the wall surfaces of the grooves 52 and 54 of the hub outer ring 30. Also rotate.

  As shown in FIG. 4, the induction heating coil 70 includes an annular upper annular coil 72 formed in an upper stage, an annular lower annular coil 74 formed below the upper annular coil 72, an upper annular coil 72 and a lower stage. A first linear connection coil 76 that connects the annular coil 74, a second connection coil 78 that connects the upper annular coil 72 to the high frequency power supply 80, and a third connection coil 79 that connects the lower annular coil 74 to the high frequency power supply 80. Have The upper annular coil 72 is disposed so as to face the groove 54. The lower annular coil 74 is disposed to face the groove 52. The upper annular coil 72 and the lower annular coil 74 have the same diameter and the same wire diameter. The high-frequency current flowing through the induction heating coil 70 becomes an arrow shown in FIG. 4 at a certain moment.

  A disk-shaped core 82 is disposed on the upper annular coil 72. The diameter of the disk-shaped core 82 is substantially equal to the diameter of the upper annular coil 72. Further, the thickness of the disk-shaped core 82 is substantially equal to the thickness of the upper annular coil 72. The core 82 is made of ferrite (a magnetic material made of a group of crystalline crystals of a compound containing an iron oxide).

  A disc-shaped core 84 is disposed between the upper annular coil 72 and the lower annular coil 74. The diameter of the disk-shaped core 84 is substantially equal to the diameter of the upper annular coil 72. The thickness of the disk-shaped core 84 is substantially equal to the distance from the upper annular coil 72 to the lower annular coil 74 and is located between the groove 52 and the groove 54. The core 84 is made of ferrite. A plurality of coolant injection ports 82 a and 82 b are formed in the upper and lower portions of the core 84. The coolant sprayed from the coolant spray port 82a is sprayed into the groove 54, and the groove 54 is cooled. The coolant sprayed from the coolant spray port 82b is sprayed into the groove 52, and the groove 52 is cooled.

  A disk-shaped core 86 is disposed under the lower annular coil 74. The diameter of the disk-shaped core 86 is substantially equal to the diameter of the lower annular coil 74. In addition, the thickness of the disk-shaped core 86 is slightly larger than the thickness of the lower annular coil 74. The core 86 is made of ferrite. The three cores 82, 84, 86 described above have a function of converging the magnetic flux and not diffusing it.

  The induction hardening device 60 has a cup-type upper center 90 (an example of a contact jig according to the present invention) that surrounds and contacts the outer peripheral surface of the thin portion 38 of the hub outer ring 30. The cup-type upper center 90 covers the thin portion 38 from above the hub outer ring 30 with the cup turned down, and an annular contact portion 92 is in contact with the outer peripheral surface of the thin portion 38. The cup-type upper center 90 is for preventing the thin portion 38 from being deformed during heating or cooling.

  A copper shield member 94 is fixed to the inner portion of the cup-type upper center 90. The shield member 94 is detachably fixed to the cup-type upper center 90 with a bolt 95 or the like. The copper shield member 94 is disk-shaped, and its thickness is substantially equal to the distance from the bottom of the cup-type upper center 90 to the upper end of the thin portion 38. The peripheral edge 94a of the shield member 94 protrudes downward. The peripheral edge portion 94 a is positioned so as to face the inner peripheral surface of about one third of the upper portion of the thin portion 38 and is in contact with the thin portion 38. That is, the inner peripheral surface of about one third of the upper portion of the thin portion 38 is covered with the peripheral edge portion 94 a of the shield member 94. The shield member 94 only needs to be made of a nonmagnetic material that is conductive and difficult to pass magnetic flux, and may be made of aluminum, silver, nickel, or the like in addition to copper. In addition, you may form the shield member 94 in the cyclic | annular thing only of the peripheral part 94a.

  An induction hardening method for hardening the wall surfaces of the grooves 52 and 54 of the hub outer ring 30 using the induction hardening device 60 will be described with reference to FIG.

  FIG. 5 is a schematic diagram illustrating an example of a magnetic flux generated by the induction heating coil.

  By supplying electric power from the high frequency power supply 80 to the induction heating coil 70, a current as shown in FIG. 4 flows through the induction heating coil 70 at a certain moment. By such an alternating current, as shown in FIG. 5, the alternating magnetic flux 72a generated by the alternating current flowing through the upper annular coil 72 penetrates the wall surface 54a of the groove 54, whereby an eddy current is applied to the wall surface 54a of the groove 54. The wall surface 54a of the groove 54 is heated to the quenching temperature by the induced Joule heat of the eddy current. The wall surface 52a of the groove 52 is similarly heated to the quenching temperature. Immediately thereafter, the wall surfaces 52a and 54a of the grooves 52 and 54 are rapidly cooled and hardened by spraying the coolant from the plurality of coolant spray ports 82a and 82b.

  In addition, when the wall surfaces 52a and 54a of the grooves 52 and 54 are induction-heated and rapidly cooled, the coolant may be sprayed to the outer peripheral surface of the thin portion 38. In this case, the thin portion 38 can be further reliably prevented from being heated, and the peripheral portion of the groove 54 can be further reliably prevented from being inadvertently cured.

  Here, the wall surface 54a is examined.

  Most of the alternating magnetic flux 72 a generated by the alternating current flowing through the upper annular coil 72 is converged on the core 82 and passes through the core 82. However, a part of the alternating magnetic flux 72 b is directed to the thin portion 38 without being converged on the core 82, and a shield member 94 is disposed in the vicinity of the thin portion 38. For this reason, since the magnetic flux directed toward the thin portion 38 is difficult to pass through the shield member 94, an eddy current is hardly induced in the thin portion 38, and the thin portion 38 is hardly heated. In this case, when the peripheral edge 94a of the shield member 94 is too close to the groove 54, the upper part of the wall surface 54a of the groove 54 is not easily heated to the quenching temperature. Even when it is difficult to heat the lower portion of the thin portion 38, the peripheral portion 94a is not directly faced or brought into contact with the lower portion.

  By not hardening the thin portion 38 as described above, it is possible to form a shallow hardened layer as designed on the upper surface of the wall surface 54a of the groove 54 and to prevent the thin portion 38 from being cracked.

  In the above description, the hub outer ring 30 is taken as an example. However, the present invention can be applied to the case where a hardened layer is formed on the wall surface of the cylindrical member in which a groove extending in the circumferential direction is formed on the inner peripheral surface of the side wall.

It is a perspective view which shows the hub outer ring which is an example of a cylindrical member, and an upper center. It is a longitudinal cross-sectional view of a hub outer ring | wheel, and the induction heating coil inserted in the inside of a hub outer ring | wheel is also shown. It is sectional drawing which shows the induction heating coil and cup type upper center which are arrange | positioned at the hollow part of the hub outer ring | wheel. It is a perspective view which shows typically the direction of the electric current which passes an induction heating coil at a certain moment. It is a schematic diagram which shows an example of the magnetic flux generated by the induction heating coil. It is a schematic diagram which shows the conventional induction hardening method which forms a hardened layer in the wall surface of two grooves.

Explanation of symbols

30 Hub outer ring 34 Side wall 38 Thin wall portion 50 Inner peripheral surfaces 52 and 54 of the side wall Groove 60 Induction hardening coil 70 Induction heating coil 94 Shield member

Claims (11)

In the induction hardening apparatus for forming a hardened layer on the wall surface of the groove among the cylindrical members in which grooves extending in the circumferential direction are formed on the inner peripheral surface of the side wall,
An induction heating coil disposed facing the wall surface of the groove;
An induction hardening apparatus, comprising: a shield member that is arranged to face a portion in the vicinity of the wall surface of the groove of the inner peripheral surface of the side wall of the cylindrical member and that is difficult to pass magnetic flux. A first groove and a second groove extending in the circumferential direction are formed on the inner peripheral surface of the side wall at a predetermined interval in the height direction, and the second groove and the second groove are sandwiched between the first groove and the side wall. In the induction hardening apparatus for forming a hardened layer on the wall surfaces of the first and second grooves of the cylindrical member in which the thickness of the opposite side portion on the opposite side is thinner than the thickness of the vicinity portion of the second groove ,
An induction heating coil disposed facing the wall surfaces of the first and second grooves;
An induction hardening apparatus, comprising: a shield member arranged to face the inner peripheral surface of the opposite side portion of the side wall and difficult to pass magnetic flux. The shield member is
The induction hardening apparatus according to claim 1 or 2, wherein the induction hardening apparatus is made of a conductive and nonmagnetic material. The shield member is
The induction hardening apparatus according to claim 1, 2 or 3, wherein the induction hardening apparatus is made of any one of copper, aluminum, silver and nickel. The shield member is
5. The high-frequency wave according to claim 1, wherein the high-frequency wave is disposed so as to face an adjacent portion adjacent to the wall surface of the first groove in the inner peripheral surface of the side wall. Quenching equipment. The shield member is
The induction hardening apparatus according to any one of claims 1 to 5, wherein the induction hardening apparatus is disposed in contact with the inner peripheral surface. The opposite side portion is formed in an annular shape,
The shield member is
The induction hardening device according to any one of claims 2 to 6, wherein the induction hardening device is an annular device arranged along an inner peripheral surface of the opposite side portion. The induction hardening apparatus according to claim 7, further comprising a contact jig that surrounds and contacts the outer peripheral surface of the opposite side portion. The shield member is
The induction hardening apparatus according to claim 8, wherein the induction hardening apparatus is detachably fixed to the holding jig. A first groove and a second groove extending in the circumferential direction are formed on an inner peripheral surface of the side wall at a predetermined interval in the height direction, and the second groove sandwiching the first groove among the side walls and In the induction hardening method of forming a hardened layer on the wall surfaces of the first and second grooves of the cylindrical member, the thickness of the opposite side portion on the opposite side is thinner than the thickness of the vicinity portion of the second groove,
While placing the induction heating coil facing the wall surfaces of the first and second grooves,
Face the inner peripheral surface of the opposite side portion of the side wall, arrange a shield member that is difficult to pass magnetic flux,
A high-frequency quenching method characterized in that a high-frequency current is passed through the induction heating coil to heat the wall surfaces of the first and second grooves to a predetermined quenching temperature to quench them. When heating and quenching the wall surfaces of the first and second grooves to a predetermined quenching temperature,
The induction hardening method according to claim 10, wherein a coolant is sprayed on an outer peripheral surface of the opposite side portion of the side wall.

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