JP2007204834A - Heat treatment method for gear member and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment method for a gear member and a device therefor where self-annealing treatment is performed by utilizing a part of the heat applied to a gear member upon quenching, thus energy saving is attained, and the simplification of equipment or the like can be realized. <P>SOLUTION: Each gear part 11b in an inner ring 11 is arranged so as to face a high frequency inductor 24 in the heat treatment device over the whole circumference. In this state, high frequency electric current is fed to the high frequency inductor 24 from the outside, and each gear part 11B in the inner ring 11 is collectively heated to a set temperature. Thereafter, cooling water is fed from the side of a passage member 26 in a state where the high frequency inductor 24 is stopped, thus each gear part 11B in a high temperature state is collectively cooled to a prescribed cooling temperature. Then, at the time when each gear part 11B reaches the prescribed cooling temperature, the feed of the cooling water is immediately stopped, thus remaining heat is secured on the side of the ring body 11A in the inner ring 11, and, by utilizing the remaining heat at this time, each gear part 11B in the inner ring 11 is self-tempered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a gear suitably used for quenching and tempering gear members that require wear resistance and impact resistance, such as a power transmission gear, an inner ring or an outer ring of a turning wheel, and the like. The present invention relates to a member heat treatment method and apparatus.

  In general, gear members used for machine parts such as construction machines are usually hardened, tempered, etc. for a plurality of tooth portions after being formed into a predetermined gear shape using a machining means such as forging and cutting. The finished product is made by giving the appropriate hardness and rigidity to each tooth part.

  In particular, the gear member is required to have impact resistance, pitting resistance, and wear resistance on the surface (tooth surface) side of each tooth portion, and requires a certain degree of toughness on the inner side. It is known. And after performing the quenching process with respect to the gear member, the internal stress of the gear member is relieved by performing a tempering process at a temperature sufficiently lower than the quenching temperature (for example, a temperature of 200 to 250 ° C.). (For example, refer to Patent Document 1).

  That is, the gear member after the quenching treatment can be increased in hardness and rigidity, but has a drawback that residual stress is generated due to a structural transformation (martensitic transformation) due to rapid cooling, resulting in poor toughness. Therefore, the tempering process is performed on the gear member after quenching to relieve internal stress and toughness.

  In addition, when manufacturing camshafts of automobile engines as castings (castings) by the mold casting method, the internal temperature (heat during casting) when the casts are released from the molds is used. In addition, a heat treatment method for a die casting product in which heat treatment including self-tempering is performed on the cast product is known (see, for example, Patent Document 2).

JP 2000-282145 A JP-A-11-350030

  By the way, in the above-described conventional technique (Patent Document 1), the quenching process and the tempering process are performed with the same high-frequency inductor, thereby simplifying the entire heat treatment apparatus and saving space. However, even in this case, since the same high frequency inductor is reciprocated in one direction and the other direction in the quenching process and the tempering process, there is a problem that extra time and labor are spent on the movement (reciprocation) of the high frequency inductor. is there.

  In the tempering step, the gear member is heated again to a predetermined tempering temperature by supplying power to the high-frequency inductor, so that the energy consumption is excessively increased and energy saving cannot be realized. Further, in the quenching process, after the gear member is heated to a high temperature, rapid cooling is performed to a sufficiently low temperature using a cooling medium, so that there is a problem that extra cooling energy is consumed.

  On the other hand, in the other prior art (Patent Document 2), the internal temperature (heat at the time of casting) when the cast product is released from the mold is used for self-tempering the cast product. There is an advantage that the tempering process (processing) for the cast product can be made efficient, energy consumption can be reduced, and energy saving can be realized.

  However, the self-tempering process in this case uses heat generated when the molten metal is poured into the mold (heat during casting), and performs a quenching process in advance to increase the hardness and rigidity of the product. is not. For this reason, the technical background is different from the case where a gear part molded into a predetermined gear shape using a machining means such as forging and cutting is subjected to quenching and tempering.

  In addition, as a material of a cast product using a mold, for example, a cast iron material having a carbon content of 2 to 3% or more is used, so that it is not suitable for a gear member that requires wear resistance, impact resistance, or the like. Is. And as a raw material of such a gear member, for example, it is often formed using hypoeutectoid steel having a carbon content of less than 0.8%.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to perform heat treatment on the gear member by performing a self-tempering process using a part of heat input applied to the gear member during quenching. An object of the present invention is to provide a gear member heat treatment method and apparatus capable of efficiently performing the entire process, saving energy, and simplifying equipment.

  In order to solve the above-described problems, the present invention is applied to a gear member heat treatment method in which a gear member having a plurality of tooth portions is formed by machining, and then the respective tooth portions are quenched and tempered.

  And the feature of the heat treatment method adopted by the invention of claim 1 is that a heating step of heating each tooth portion collectively to a preset temperature for quenching each tooth portion of the gear member, and the setting A cooling process in which each tooth portion of the gear member heated to a temperature is rapidly cooled by a cooling medium from the outside, and each tooth portion reaches a predetermined cooling temperature and there is residual heat on the base material side of the gear member. It comprises a self-tempering step in which cooling by the cooling medium is stopped and tempering is performed on each tooth portion using residual heat on the base material side.

  According to a second aspect of the present invention, the gear member is formed using hypoeutectoid steel having a carbon content of less than 0.8%.

  According to a third aspect of the present invention, the gear member is used as an inner ring or an outer ring that constitutes a swivel wheel of a swivel construction machine and in which the plurality of tooth portions are integrally formed on the inner peripheral side or the outer peripheral side. .

According to the invention of claim 4, the set temperature in the heating step is a temperature equal to or higher than the austenitization transformation point (A ₃ ), and the predetermined cooling temperature is equal to or lower than the martensitic transformation end point (Mf). The temperature is set.

  According to the invention of claim 5, in the self-tempering step, the entire gear member is maintained at a temperature of 180 to 280 ° C.

  On the other hand, the invention of claim 6 is a gear member heat treatment apparatus for performing quenching and tempering on each tooth portion after forming a gear member having a plurality of tooth portions by machining. A high-frequency inductor that is disposed opposite to each tooth part and is heated from the outside by supplying power from the outside, and a cooling medium supplied from the outside in a state where power supply to the high-frequency inductor is stopped Cooling means for collectively cooling the tooth portions, and the gear member covers the base material side excluding the tooth portions from the outside to prevent the cooling medium from adhering to the base material side. The shielding member is provided.

  As described above, according to the first aspect of the present invention, the quenching process performed after the gear member is formed by machining is performed at a time until each tooth portion of the gear member is set to a predetermined set temperature for quenching. The heating step for heating and the cooling step for rapidly cooling each tooth portion of the gear member heated to the set temperature from the outside by a cooling medium are performed. Tempering is performed on each tooth by using the residual heat on the base material side while immediately stopping the cooling by the cooling medium when the temperature reaches the temperature and there is residual heat on the base material side of the gear member. I am doing so. For this reason, unlike the prior art, there is no need to feed the high-frequency inductor and reheat the gear member to a predetermined tempering temperature, which can suppress excessive energy consumption during the tempering process, thereby saving energy. Can be realized.

  Therefore, by utilizing a part of the heat input applied to the gear member in the quenching process (heating step) performed on the gear member after machining, each tooth portion of the gear member is used as residual heat on the base material side. It can self-temper and eliminates the extra energy consumption for the tempering process. Further, even in the stage of quenching treatment for the gear member, when each tooth portion reaches a predetermined cooling temperature in the cooling process performed after the heating process, the supply of the cooling medium is immediately stopped and the residual heat is supplied to the base material side of the gear member. Therefore, it is possible to suppress excessive consumption of cooling energy at this time, to efficiently perform the entire heat treatment process for the gear member, to realize energy saving, and to simplify the equipment. Etc. can also be aimed at.

  In the invention according to claim 2, since the gear member is formed using hypoeutectoid steel having a carbon content of less than 0.8%, for example, compared with a casting material (cast product) or the like, The mechanical strength, rigidity, and the like can be increased, and wear resistance, impact resistance, and the like can be imparted to the teeth of the gear member in a state where heat treatment is performed.

  Further, the invention according to claim 3 is a heat treatment target of an inner ring and an outer ring constituting a turning wheel of a turning construction machine, in which a plurality of tooth portions are integrally formed on the inner peripheral side or the outer peripheral side. It can be used as a gear member, and the wear resistance, impact resistance, etc. required for the gear portion of the swivel ring can be satisfactorily ensured by heat treatment including a self-tempering step.

In the invention according to claim 4, the set temperature in the heating step is set to a temperature equal to or higher than the austenitization transformation point (A ₃ ), and the cooling temperature in the cooling step is equal to or lower than the martensitic transformation end point (Mf). By setting the temperature, part of the heat input applied to the gear member in the heating process can be effectively used as the residual heat on the base material side, and each tooth portion of the gear member can be efficiently self-tempered. Can do.

  In the invention according to claim 5, the entire gear member can be maintained at a temperature of 180 to 280 ° C. in the self-tempering step, and the tempering process for each tooth portion of the gear member can be efficiently performed.

  On the other hand, in the invention described in claim 6, for example, a high frequency inductor is provided so as to face each tooth part of a gear part formed into a predetermined gear shape by using a machining means such as forging and cutting. In a state of being arranged, by supplying a high-frequency current to the high-frequency inductor from the outside, each tooth portion of the gear member can be heated up to a set temperature for quenching, and thereafter the power supply to the high-frequency inductor is supplied. By supplying a cooling medium from the outside to the cooling means in a stopped state, each tooth portion in a high temperature state can be collectively cooled to a predetermined cooling temperature. And when each tooth part reaches a predetermined cooling temperature, the supply of the cooling medium is immediately stopped, so that the residual heat can be secured on the base material side of the gear member, and the residual heat at this time is utilized. Thus, each tooth portion of the gear member can be self-tempered.

  Further, since the base material side excluding each tooth portion of the gear member is covered from the outside with a shielding member, the cooling medium from the cooling means is prevented from adhering to the base material side of the gear member. Can be intensively supplied to each tooth portion of the gear member for efficient quenching, and sufficient residual heat can be ensured on the base material side of the gear member by the shielding member. Thereby, the whole heat treatment process with respect to the gear member can be efficiently performed, and energy saving or the like can be achieved.

  Hereinafter, a gear member heat treatment apparatus employed in an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  Here, FIG. 1 thru | or FIG. 6 shows the 1st Embodiment of this invention, and in this embodiment, an inner ring is used as a gear member among the inner ring | wheel and outer ring | wheel which comprise the turning ring | wheel of a turning type construction machine. The case where it is used will be described as an example.

  In the figure, reference numeral 1 denotes a hydraulic excavator as a swivel construction machine. The hydraulic excavator 1 includes a crawler type lower traveling body 2 capable of self-propelling as shown in FIG. The upper revolving body 3 mounted so as to be able to swivel via the wheel 10 and a work device 8 described later are roughly configured. The lower traveling body 2 includes a track frame 2A on which a later-described turning wheel 10 is mounted.

  Reference numeral 4 denotes a revolving frame that constitutes the frame of the upper revolving structure 3. The revolving frame 4 has a working device 8 (described later) attached to its front side so that it can be raised and lowered, and a counterweight 6 (described later) attached to its rear side. Yes.

  Reference numeral 5 denotes a cab that constitutes a driver's cab disposed on the left side of the front portion of the revolving frame 4, and a driver's seat on which the operator is seated or seated, an operating lever, and an operating pedal (all not shown). Etc. are arranged.

  6 is a counterweight provided on the rear end side of the revolving frame 4. The counterweight 6 is detachably mounted on the rear end side of the revolving frame 4, and the entire upper revolving unit 3 with respect to the front working device 8. The weight balance is taken. In addition, a building cover 7 (described later) that houses an engine (not shown) or the like is provided on the front side of the counterweight 6.

  Reference numeral 7 denotes a building cover which is positioned between the cab 5 and the counterweight 6 and is erected on the revolving frame 4. The building cover 7 is formed by using a plurality of metal panels made of, for example, thin steel plates. A machine room (not shown) in which an engine and the like are housed is defined.

  8 is a working device provided at the front portion of the upper swing body 3 so as to be able to move up and down. The working device 8 performs excavation work such as earth and sand with a bucket 9 as a working tool provided on the tip side thereof. It is.

  Reference numeral 10 denotes a turning wheel provided between the lower traveling body 2 and the upper turning body 3. The turning wheel 10 includes an inner ring 11 as a gear member and a plurality of outer rings on the outer side of the inner ring 11 as shown in FIG. And an outer ring 13 rotatably provided through a steel ball 12 (roller). The outer ring 13 of the turning wheel 10 is fixed to the turning frame 4 of the upper turning body 3 with bolts 14 or the like. The inner ring 11 is fixed to the track frame 2A of the lower traveling body 2 using bolts 15 or the like.

  Here, the inner ring 11 of the turning wheel 10 includes, for example, carbon steel for mechanical structure (S48C) among hypoeutectoid steel having a carbon content of less than 0.8%. As shown, it is formed as a ring gear (internal gear).

  The inner ring 11 of the turning wheel 10 includes a ring body 11A that is a base material of the gear member, a plurality of tooth portions 11B that are integrally formed on the inner peripheral side of the ring body 11A, and that are formed of teeth that extend over the entire circumference, and a ring body. It is formed of a substantially semicircular ball housing groove 11C formed on the outer peripheral side of 11A and housing the steel ball 12 of the swivel wheel 10.

  Further, as shown in FIG. 3, the inner ring 11 is formed with a screw hole 11F on the end surface 11E side of the upper and lower end surfaces 11D and 11E that are arranged on the track frame 2A. The bolt 15 shown in FIG. 2 is screwed to 11F.

  Reference numeral 16 denotes a turning speed reducer provided on the turning frame 4. The speed reducer 16 is rotationally driven by a turning hydraulic motor (not shown) and transmits the rotation output to the pinion 17. Then, the pinion 17 meshes with the tooth portion 11 </ b> B of the inner ring 11 and transmits the rotation output from the reduction gear 16 side to the inner ring 11. Thereby, the turning frame 4 of the upper turning body 3 is driven to turn through the turning wheel 10 on the track frame 2A of the lower traveling body 2.

  Next, 21 is a heat treatment apparatus for quenching and tempering each tooth part 11B of the inner ring 11, and the heat treatment apparatus 21 includes upper and lower annular plates 22, as shown in FIGS. 23, a high-frequency inductor 24 (described later) provided between the annular plates 22 and 23, and a cooling water passage member 26.

  The annular plates 22 and 23 are formed as an annular plate body from a rigid material having electrical insulation, and constitute a casing of the heat treatment apparatus 21. Further, of the annular plates 22 and 23, for example, the annular plate 22 located on the upper side is formed with a through hole 22A (see FIG. 4) on the center side thereof, and the passage member 26 described later has an inside of the through hole 22A. Cooling water is supplied from the outside through a pipe (not shown) or the like inserted through the pipe.

  Reference numeral 24 denotes a high-frequency inductor that collectively heats each tooth portion 11B of the inner ring 11, and the high-frequency inductor 24 extends over the entire circumference radially inward of each tooth portion 11B of the inner ring 11 as shown in FIGS. It is formed as an opposing annular body, and its upper and lower both sides are covered with annular plates 22 and 23 made of an insulator. The high-frequency inductor 24 incorporates a high-frequency coil (not shown) extending over the entire circumference thereof, and is fed with high-frequency power from an external high-frequency generator (not shown), whereby each tooth of the inner ring 11 is fed. The part 11B is induction-heated all over the circumference.

  Further, as shown in FIG. 5, the high-frequency inductor 24 is provided with a large number of injection holes 25, 25,..., And these injection holes 25 are arranged in the height (upper and lower) direction and the circumferential direction of the high-frequency inductor 24. Are spaced apart from each other. And each injection hole 25 comprises a cooling means with the below-mentioned channel | path member 26, and supplies the below-mentioned cooling water toward each tooth | gear part 11B of the inner ring | wheel 11 by injection.

  Reference numeral 26 denotes a passage member serving as a cooling means sandwiched between the annular plates 22 and 23 together with the high-frequency inductor 24. The passage member 26 is a ring-shaped high-frequency inductor 24 as shown in FIGS. It is formed as an annular body that is located on the inner side in the radial direction and is provided in contact with the inner peripheral surface thereof. In the passage member 26, an annular passage 27 extending over the entire circumference, and a number of liquid passages 28, 28 with one side communicating with the annular passage 27 and the other side communicating with the injection holes 25 of the high-frequency inductor 24. , ... are formed.

  Here, the annular passage 27 of the passage member 26 is connected to a cooling medium supply source (not shown) disposed outside the annular plates 22 and 23 via the pipe or the like. It is introduced between the annular plates 22 and 23 through 22A (see FIG. 4). The annular passage 27 of the passage member 26 supplies cooling water as a cooling medium supplied through the piping to the injection holes 25 of the high-frequency inductor 24 from a large number of liquid passages 28, while It ejects from the hole 25 toward each tooth part 11B of the inner ring 11.

  Thereby, each tooth part 11B of the inner ring 11 heated at once by the high frequency inductor 24 is rapidly cooled by the cooling water from each injection hole 25 at once. Each tooth portion 11B of the inner ring 11 is subjected to quenching treatment as indicated by a characteristic line 29 shown by a solid line in FIG.

  The heat treatment apparatus 21 for the inner ring 11 according to the present embodiment has the above-described configuration. Next, the heat treatment method will be described.

  First, the inner ring 11 of the turning wheel 10 is formed as a ring gear using, for example, carbon steel for mechanical structure (S48C) among hypoeutectoid steel having a carbon content of less than 0.8%, and the inner ring 11 (ring On the inner peripheral side of the body 11A), a large number of tooth portions 11B, 11B,... Are formed over the entire periphery by using machining means such as forging and cutting.

  4 and 5, the inner ring 11 is positioned with respect to the heat treatment device 21, and the teeth 11B, 11B,... Of the inner ring 11 face the high frequency inductor 24 of the heat treatment device 21 over the entire circumference. Arrange them so that they face each other. Further, a temperature sensor (not shown) or the like is disposed on or in contact with the inner ring 11 to monitor (monitor) the temperature change of each tooth portion 11B.

  Next, in this state, high-frequency power is supplied from the outside to a high-frequency coil (not shown) of the high-frequency inductor 24, and each tooth portion 11B of the inner ring 11 made of carbon steel is collectively fed from the radially inner side to the entire circumference by induction heating. And heating (heating process).

As a result, each tooth portion 11B of the inner ring 11 is equal to or higher than the set temperature T1 for quenching predetermined from the room temperature state, that is, the austenitization transformation point (A ₃ ) or more as indicated by a solid line in FIG. It is heated to a temperature T1 (for example, a temperature exceeding 900 ° C.). The time required for this heating step is about 65 to 75 seconds as shown in FIG.

  And in the stage where each tooth | gear part 11B was heated to preset temperature T1, the electric power feeding to the high frequency inductor 24 is stopped immediately, and cooling water is supplied toward the annular channel | path 27 of the channel | path member 26 from the exterior. Thereby, the cooling water which is a cooling medium is ejected toward each tooth surface of each tooth | gear part 11B from each liquid flow path 28 of the channel | path member 26, and each injection hole 25 of the high frequency inductor 24 (cooling process).

  Thereby, each tooth | gear part 11B of the inner ring | wheel 11 heated with the high frequency inductor 24 is rapidly cooled collectively with cooling water, and all the tooth | gear parts 11B are cooled temperature T2 below the martensitic transformation end point (Mf) ( For example, it is rapidly cooled to a predetermined temperature of about 50 to 100 ° C. The time required for this cooling step is about 25 seconds as shown in FIG.

The inner ring 11 made of carbon steel for mechanical structure (S48C) has an austenitization transformation point (A ₃ ) of about 760 ° C. and a martensite transformation start point (Ms) of about 360 ° C., and the martensite transformation. The end point (Mf) is about 240 ° C., for example.

  Next, each tooth part 11B of the inner ring 11 reaches a predetermined cooling temperature T2, and cooling with the cooling water is immediately stopped when there is residual heat on the ring body 11A (base material) side of the inner ring 11. And it tempers with respect to each tooth | gear part 11B by allowing the inner ring | wheel 11 to cool in air | atmosphere, utilizing the residual heat by the side of the ring body 11A (self-tempering process).

  In this case, a part of the heat input applied to the inner ring 11 in the heating process is left on the base material side in the ring body 11A as a base material of the inner ring 11 as shown by a characteristic line 30 shown by a one-dot chain line in FIG. It remains as heat, and the ring body 11A side is in a temperature state equal to or higher than the martensitic transformation end point (Mf), for example, even at the end of the cooling step.

  Therefore, in the self-tempering step shown in FIG. 6, the temperature of each tooth portion 11B of the inner ring 11 is gradually increased using the residual heat on the ring body 11A side, and, for example, at 140 to 150 seconds shown in FIG. The part 11B can be heated to a temperature T3 (for example, about 180 ° C.).

  As described above, in the self-tempering step, the inner ring 11 is allowed to cool in the atmosphere, so that the entire inner ring 11 is maintained at a temperature before and after the martensite transformation end point (Mf), for example, a temperature of 180 to 280 ° C. The tempering process for each tooth portion 11B of the inner ring 11 can be performed only by cooling in the atmosphere.

  Thus, according to the present embodiment, the quenching process performed after forming a large number of tooth portions 11B on the inner peripheral side of the inner ring 11 by machining, the predetermined quenching settings for each tooth portion 11B of the inner ring 11 are performed. It is performed by a heating process that heats to a temperature T1 at once and a cooling process that rapidly cools each tooth portion 11B of the inner ring 11 that has been heated to a set temperature T1 with cooling water from the outside.

  Then, in the subsequent self-tempering step, each tooth portion 11B reaches a predetermined cooling temperature T2 and there is residual heat on the ring body 11A side of the inner ring 11, while immediately stopping the cooling with the cooling water, the ring body 11A By using the residual heat on the side, tempering for each tooth portion 11B is performed.

  For this reason, as described in the prior art, it is not necessary to drive the high-frequency inductor at the stage of the tempering process (heating the inner ring 11 again up to a predetermined tempering temperature), thereby suppressing excessive energy consumption in the tempering process. And energy saving can be realized.

  That is, by using a part of the heat input applied to the inner ring 11 in the quenching process (heating process) performed on the inner ring 11 after machining as the residual heat on the ring body 11A (base material) side, the inner ring 11 is used. Each tooth portion 11B can be self-tempered, and unnecessary energy consumption required for the tempering process can be eliminated.

  Even in the quenching process for the inner ring 11, when each tooth portion 11B reaches a predetermined cooling temperature T2 in the cooling process performed after the heating process, the supply of the cooling water is immediately stopped and the ring body 11A side of the inner ring 11 is stopped. Therefore, it is possible to prevent excessive cooling energy from being consumed at this time, to efficiently perform the entire heat treatment process for the inner ring 11, and to realize energy saving. It is possible to simplify the process.

  In the present embodiment, the inner ring 11 that is a gear member to be heat-treated is, for example, carbon steel for mechanical structure (S48C) among hypoeutectoid steels having a carbon content of less than 0.8%. Therefore, mechanical strength, rigidity, etc. can be increased as compared with a casting material having a carbon content of 2 to 3% or more. Abrasion resistance, impact resistance and the like can be sufficiently imparted to the tooth portion 11B.

  And among the inner ring 11 and the outer ring 13 constituting the turning wheel 10 of the excavator 1, the inner ring 11 in which a plurality of tooth portions 11B are integrally formed on the inner peripheral side can be used as a gear member to be heat-treated. The wear resistance, impact resistance, and the like required for the gear portion of the swivel wheel 10 can be satisfactorily ensured by heat treatment including the above-described self-tempering step.

Further, by setting the set temperature T1 in the heating step to a temperature equal to or higher than the austenitization transformation point (A ₃ ), and the cooling temperature T2 in the cooling step to a temperature lower than the martensite transformation end point (Mf), Part of the heat input applied to the inner ring 11 in the heating process can be effectively used as the residual heat on the ring body 11A side, and each tooth portion 11B of the inner ring 11 can be efficiently self-tempered. Further, in the self-tempering step, the entire inner ring 11 can be maintained at a temperature of 180 to 280 ° C., and the tempering process for each tooth portion 11B of the inner ring 11 can be efficiently performed only by cooling in the air. .

  Next, FIG. 7 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted. And

  However, the feature of the present embodiment is that one of the cooling water sprayed from each spray hole 25 toward the tooth portion 11B by covering the ring body 11A on the base material side of the inner ring 11 with the shielding member 31 from above. This is to prevent the portion from adhering to the ring body 11 </ b> A side of the inner ring 11.

  Here, the shielding member 31 is formed as an annular flat plate using a material having low thermal conductivity (for example, a ceramic material, a synthetic resin material, etc.), and covers the end surface 11D on the upper side of the inner ring 11 from above. In this case, the shielding member 31 does not cover each tooth portion 11 </ b> B of the inner ring 11, and is disposed in contact with the upper surface of the ring body 11 </ b> A of the end surface 11 </ b> D of the inner ring 11.

  The shielding member 31 allows the cooling water injected from each injection hole 25 of the heat treatment device 21 to adhere to the tooth portion 11B of the inner ring 11, but a part of the cooling water at this time is sprayed upward. When coming, the cooling water is prevented from adhering to the ring body 11A side of the inner ring 11 by guiding the flow of the cooling water to the upper side of the shielding member 31 in the direction of the arrow W1 indicated by the dotted line in FIG. .

  Further, among the cooling water sprayed from the respective injection holes 25 of the heat treatment apparatus 21, the cooling water sprayed downward from between the tooth portion 11B of the inner ring 11 and the high frequency inductor 24 is indicated by a dotted line in FIG. Since it naturally falls in the direction of the arrow W2, the cooling water at this time does not adhere to the lower surface side of the ring body 11A. For this reason, it is not necessary to provide a shielding member or the like on the lower surface (end surface 11E) side of the ring body 11A.

  Thus, even in the present embodiment configured as described above, when the heat treatment is performed on the tooth portion 11B of the inner ring 11, the first quenching and tempering processes are performed in the same manner as in the first embodiment. It is possible to obtain substantially the same operational effects as in the embodiment. However, in the present embodiment, the ring body 11A of the inner ring 11 is covered with the shielding member 31 from the upper side.

  For this reason, in the cooling process of the quenching process with respect to the tooth part 11B of the inner ring 11, a part of the cooling water injected from the respective injection holes 25 of the heat treatment device 21 toward the tooth part 11B adheres to the ring body 11A side of the inner ring 11. Therefore, the cooling water can be intensively supplied to each tooth portion 11B of the inner ring 11 to efficiently cool each tooth portion 11B.

  As a result, since sufficient residual heat can be secured by the shielding member 31 on the base material (ring body 11A) side of the inner ring 11, the entire heat treatment process for the inner ring 11 is also possible as compared with the first embodiment. Can be performed more efficiently, and energy saving can be achieved.

  Next, FIG. 8 shows a third embodiment of the present invention. In this embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted. And

  However, the present embodiment is characterized in that the ring body 11A on the base material side of the inner ring 11 is covered with the shielding member 41 from above, and cooling air is injected onto the shielding member 41 in the direction of arrow a and supplied. In this configuration, the blower 42 is provided.

  Here, the shielding member 41 is formed in substantially the same manner as the shielding member 31 described in the second embodiment, and covers the end surface 11D on the upper side of the inner ring 11 from above. The blower 42 constitutes a cooling means together with the passage member 26 and the like, and jets cooling air supplied from a pressurized air source (not shown) such as an air tank through the air conduit 43 in the direction of arrow a.

  In this case, among the cooling water sprayed from the respective injection holes 25 of the heat treatment apparatus 21, the cooling water sprayed downward from between the tooth portion 11B of the inner ring 11 and the high frequency inductor 24 is indicated by a dotted line in FIG. Naturally falls in the direction indicated by the arrow W2. On the other hand, the cooling water sprayed upward from between the tooth portion 11B of the inner ring 11 and the high frequency inductor 24 (cooling water flowing in the direction of the arrow W3 indicated by the dotted line in FIG. 8) is sent from the blower 42 in the direction indicated by the arrow a. The flow direction is limited by the cooling air that is jetted out and the shielding member 41, and the cooling water does not adhere to the ring body 11 </ b> A side of the inner ring 11.

  And most of the cooling water at this time comes to fall spontaneously in the direction of arrow W2 in FIG. 8 from between the tooth portion 11B of the inner ring 11 and the high frequency inductor 24 downward. Moreover, the cooling air which ejected from the air blower 42 cools each tooth | gear part 11B of the inner ring | wheel 11 which is not covered with the shielding member 41 from an upper side with an air flow. And the cooling air from the air blower 42 does not contact (adhere) to the upper surface of the ring body 11A covered with the shielding member 41 in the end surface 11D of the inner ring 11, and the ring body 11A side is not subjected to the heating process. Residual heat can be secured.

  Thus, even in the present embodiment configured as described above, when the heat treatment is performed on the tooth portion 11B of the inner ring 11, the first quenching and tempering processes are performed in the same manner as in the first embodiment. It is possible to obtain substantially the same operational effects as in the embodiment. However, in the present embodiment, the ring body 11A of the inner ring 11 is covered with the shielding member 41 from above, and the blower 42 is provided on the shielding member 41 to inject and supply cooling air.

  For this reason, in the cooling process of the quenching process for the tooth portion 11B of the inner ring 11, the inner ring 11 is formed by the cooling water sprayed from the respective injection holes 25 of the heat treatment device 21 toward the tooth portion 11B and the cooling air from the blower 42. Each tooth part 11B can be cooled more reliably. Further, the shielding member 41 can prevent the cooling water and cooling air from adhering to and coming into contact with the ring body 11A side of the inner ring 11 at this time, and the cooling water and the cooling air are concentrated on each tooth portion 11B of the inner ring 11. Can be supplied to.

  As a result, since sufficient residual heat can be secured by the shielding member 31 on the base material (ring body 11A) side of the inner ring 11, the entire heat treatment process for the inner ring 11 is also possible as compared with the first embodiment. Can be performed more efficiently, and energy saving can be achieved.

  In each of the above-described embodiments, the case where the inner ring 11 of the turning wheel 10 is used as the gear member to be heat-treated has been described as an example. However, the present invention is not limited to this. For example, as in the modification shown in FIG. 9, an annular ring body 51 </ b> A that is a base material of the gear member and an outer peripheral side of the ring body 51 </ b> A are formed over the entire circumference. Alternatively, the outer ring 51 of the turning wheel composed of a large number of tooth portions 51B, 51B,... May be used as a gear member to be heat-treated.

  Further, as the gear member to be heat-treated, for example, the pinion 17 shown in FIG. 2 may be used, and the sun gear, the internal gear (ring gear), the planetary gear, etc. of the planetary gear reduction mechanism used in the speed reducer 16 are to be heat-treated. Also good. As the gear member to be heat-treated, various gear members such as an external gear and an internal gear for power transmission may be used.

  Moreover, in the said 1st Embodiment, the high frequency inductor 24 was formed as a cyclic | annular body, and it demonstrated and demonstrated as an example the case where it arrange | positions opposing each tooth | gear part 11B of the inner ring | wheel 11 over the perimeter over radial direction. However, the present invention is not limited to this, and a plurality of (many) uneven portions are provided on the outer peripheral side of the high-frequency inductor 24 from the annular body so as to sandwich the tooth surface of each tooth portion 11B from both sides in the circumferential direction, for example. It is good also as a structure which forms and raises the induction heating performance of the high frequency inductor 24 further by these uneven | corrugated | grooved parts. This also applies to the second and third embodiments.

1 is an external view showing a hydraulic excavator provided with a turning wheel according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the turning wheel in FIG. 1 with the reduction gear for turning, etc. It is an expanded sectional view which shows the inner ring in FIG. 2 as a single body. It is a top view which shows the state which has arrange | positioned the heat processing apparatus by 1st Embodiment facing the inner peripheral side of an inner ring | wheel. It is the expanded sectional view which looked at the heat processing apparatus arrange | positioned facing the inner peripheral side of an inner ring | wheel from the arrow VV direction in FIG. It is a characteristic diagram which shows the temperature characteristic when hardening and tempering the inner ring | wheel of a turning wheel. It is an enlarged step surface figure in the same position as FIG. 5 which shows the heat processing apparatus by 2nd Embodiment. It is an enlarged step view in the same position as FIG. 5 which shows the heat processing apparatus by 3rd Embodiment. It is a top view which shows the outer ring | wheel of the turning wheel by the modification of this invention.

Explanation of symbols

1 Hydraulic excavator (swivel construction machine)
2 Lower traveling body 3 Upper revolving body 4 Turning frame 10 Turning wheel 11 Inner ring (gear member)
11A, 51A Ring body (base material)
11B, 51B Tooth part 12 Steel ball (roller)
13 Outer ring 16 Reducer for turning 17 Pinion 21 Heat treatment device 22, 23 Annular plate (insulator)
24 High-frequency inductor 25 Injection hole 26 Passage member (cooling means)
31, 41 Shielding member 42 Blower (cooling means)
51 Outer ring (gear member)
T1 Set temperature for quenching T2 Predetermined cooling temperature

Claims (6)

After forming a gear member having a plurality of tooth portions by machining, the gear member is heat-treated by quenching and tempering each tooth portion,
A heating step of heating each tooth portion at once to a predetermined set temperature in order to quench each tooth portion of the gear member;
A cooling step of rapidly cooling each tooth portion of the gear member heated to the set temperature from the outside by a cooling medium;
When each tooth portion reaches a predetermined cooling temperature and there is residual heat on the base material side of the gear member, cooling by the cooling medium is stopped, and tempering on each tooth portion is performed using the residual heat on the base material side. A heat treatment method for a gear member comprising a self-tempering step.   The gear member heat treatment method according to claim 1, wherein the gear member is formed using hypoeutectoid steel having a carbon content of less than 0.8%.   3. The method for heat-treating a gear member according to claim 1, wherein the gear member is an inner ring or an outer ring that constitutes a swivel wheel of a swivel type construction machine and in which the plurality of tooth portions are integrally formed on an inner peripheral side or an outer peripheral side. . The set temperature in the heating step is a temperature equal to or higher than the austenitization transformation point (A ₃ ), and the predetermined cooling temperature is set to a temperature equal to or lower than the martensitic transformation end point (Mf). The heat processing method of the gear member of 2 or 3.   The gear member heat treatment method according to claim 1, 2, 3, or 4, wherein in the self-tempering step, the entire gear member is maintained at a temperature of 180 to 280 ° C. A gear member heat treatment apparatus that performs hardening and tempering on each tooth portion after forming a gear member having a plurality of tooth portions by machining,
A high-frequency derivative that heats each tooth portion in a batch by being arranged opposite to each tooth portion of the gear member and fed from outside;
Cooling means for collectively cooling each tooth portion with a cooling medium supplied from the outside in a state where power supply to the high-frequency derivative is stopped,
An apparatus for heat-treating a gear member, wherein the gear member is provided with a shielding member that covers the base material side excluding the tooth portions from the outside and prevents the cooling medium from adhering to the base material side.

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