JP6185829B2 - Manufacturing method of crankshaft and external gear of eccentric oscillating speed reducer - Google Patents

Description

The present invention relates to a method of manufacturing a crank shaft and the external gear of the eccentric oscillating speed reducer equipment.

  Patent Document 1 discloses an eccentric oscillating speed reduction device.

  In this eccentric oscillating speed reducer, the external gear is in mesh with the internal gear while oscillating. And the relative rotation which arises depending on the number-of-teeth difference of an external gear and an internal gear is taken out as a deceleration output.

  In order to oscillate the external gear, the eccentric oscillating speed reduction device includes three crankshafts having eccentric portions and crankshaft gears for rotating the crankshafts. Then, by rotating the eccentric portions formed at the same position in the axial direction of the three crankshafts in synchronization with each other, the external gear is swung and internally meshed with the internal gear.

Japanese Patent Laying-Open No. 2011-158073 (FIG. 4)

  In the eccentric rocking type reduction gear, strong durability is required for the crankshaft and the external gear. On the other hand, if the strength (hardness) is increased in order to increase the durability, the finishing process becomes more difficult and the processing cost is drastically increased.

  This invention is made | formed in view of such a situation, Comprising: It makes it the subject to provide the eccentric rocking | fluctuation type deceleration device which can reduce cost further, maintaining predetermined quality.

The present invention includes an internal gear, an external gear that meshes with the internal gear, and a crankshaft that swings the external gear, and the crankshaft includes a plurality of eccentric portions and the eccentric portion. A connecting portion provided between the eccentric portion, a bearing arrangement portion where a bearing supporting the crankshaft is arranged, and a torque input portion receiving torque from the input side, and an outer periphery of the eccentric portion a method of manufacturing a crank shaft of the eccentric oscillating type speed reducer that said external gear is incorporated via the eccentric portion bearing on a step of forming an eccentric portion of the front Kifuku number, the step of forming the connecting portion If, forming a pre-Symbol axis power distribution part, and forming the torque input unit, the plurality of eccentric portions, the connecting portion, and the bearing arrangement portion, a step of performing carburization plurality The eccentric part is subjected to induction hardening and the hardness of the eccentric parts A step higher than the hardness of the bearing placement portion, the multiple eccentric portions, and performing finishing after the induction hardening process, the bearing placement portion, configured to include a step for finishing the Thus, the above-described problems are solved.

  According to the present invention, after undergoing the step of forming the crankshaft into a predetermined shape, the eccentric portion is subjected to induction hardening, and the hardness of the eccentric portion is determined to be the bearing arrangement in which the bearing supporting the crankshaft is disposed. Higher than the hardness of the part.

  Thereby, the finishing cost of the crankshaft can be reduced while maintaining the strength (hardness) required for the crankshaft.

  The present invention also relates to a method of manufacturing an external gear of an eccentric oscillating speed reducer, the step of forming a tooth portion of the external gear, and a position offset from the center of the external gear. A step of forming an offset through hole of a rotation synchronizing member that synchronizes with the rotation of the toothed gear, a step of forming a central through hole at the center of the external gear, and a step of carburizing the entire external gear. The tooth portion and the offset through hole are induction hardened, and the hardness of the tooth surface of the tooth portion and the inner peripheral surface of the offset through hole is set to any part other than the tooth surface and the inner peripheral surface of the offset through hole. And a method of manufacturing an external gear of an eccentric oscillating speed reducer characterized by including a step of making the hardness higher than the above-mentioned hardness.

  ADVANTAGE OF THE INVENTION According to this invention, the eccentric rocking | fluctuation type deceleration device which can further reduce cost can be obtained, maintaining predetermined quality.

1 is an overall cross-sectional view of an eccentric oscillating speed reducer to which a manufacturing method according to an example of an embodiment of the present invention is applied. Conceptual diagram showing the finishing process of the crankshaft of the eccentric oscillating speed reducer The conceptual diagram which shows the finishing process of the external gear of the said eccentric oscillating type reduction gear

  Hereinafter, an example of an embodiment of the present invention will be described in detail based on the drawings.

  FIG. 1 is an overall cross-sectional view of an eccentric oscillating speed reducer to which a manufacturing method according to an example of an embodiment of the present invention is applied. 2 and 3, the crankshaft and the external gear are shown in a single item in the upper left part. First, the overall configuration of the eccentric oscillating speed reducer will be described.

  The eccentric oscillating speed reducer 10 is an eccentric oscillating speed reducer called a so-called sort type. The eccentric oscillating speed reduction device 10 includes an internal gear 12 and first and second external gears 14 and 16 that are in mesh with the internal gear 12, and the axis of the internal gear 12. A plurality of (three in this example) crankshafts 18 (18A to 18C: only 18A is shown in FIG. 1) for swinging the first and second external gears 14 and 16 at a position offset by R1 from O1. It has. The crankshaft 18 corresponds to a “synchronizing member that synchronizes with the rotation of the external gear” in the present embodiment (described later).

  In the eccentric oscillating speed reduction device 10 according to this embodiment, the power of a motor (not shown) is input via the input shaft 26. An input gear 32 is directly cut and formed at the end of the input shaft 26 on the side opposite to the motor. The input gear 32 meshes simultaneously with a plurality (three in this example) of crankshaft gears 30 (30A to 30C: only 30A is shown in FIG. 1). Each crankshaft gear 30 has its own fitting hole 30p (30Ap-30Cp: only 30p is shown in FIG. 1) and a plurality (three in this example) of torque shafts 70 (70A-70C: FIG. 1). Then, only 70 is shown), and is connected to a plurality of (three in this example) crankshafts 18 respectively.

  Each crankshaft 18 includes a plurality (two in this example) of first and second eccentric parts 20 and 22, a connection part 23 between the first eccentric part 20 and the second eccentric part 22, and a crankshaft. The first and second bearing arrangement portions 19 and 21 in which the first and second crankshaft bearings 44 and 46 that support 18 are arranged, and the torque input portion 70 that receives torque from the input side are formed.

  Each first eccentric portion 20 and each second eccentric portion 22 of each crankshaft 18 are formed at the same position in the axial direction, and the eccentric phases are aligned. The eccentric phase difference between the first eccentric part 20 and the second eccentric part 22 is 180 degrees (eccentric in a direction away from each other). The first and second bearing arrangement portions 19 and 21 are formed outside the first and second eccentric portions 20 and 22 in the axial direction, respectively.

  In this embodiment, the torque input unit 70 is formed at the end of the crankshaft 18 on the axial motor side (drive source side). The torque input unit 70 has a cross-sectional shape that engages with the fitting hole 30p of the crankshaft gear 30 described above. In this embodiment, the cross section perpendicular to the axial direction of the crankshaft 18 is a regular hexagonal polygon. However, the shape of the torque input unit 70 is not particularly limited to a regular hexagon. That is, it does not necessarily have to be a regular polygon, and does not have to be a hexagon. For example, it may be a spline or a so-called D-cut shape. In this embodiment, the fitting hole 30p of the crankshaft gear 30 and the torque input unit 70 are fitted with an interference fit. The method for manufacturing the crankshaft 18 will be described in detail later.

  First and second external gears 14 and 16 are incorporated on the outer periphery of each crankshaft 18 via first and second eccentric bearings 34 and 36. The first and second external gears 14 and 16 include tooth portions 14A and 16A on the outer periphery, and the crankshaft 18 and the first external gears 14 and 16 are offset from the centers of the first and second external gears 14 and 16, respectively. The offset eccentric holes 14B and 16B through which the second eccentric bearings 34 and 36 pass are provided. The first and second external gears 14 and 16 further include central through holes 14C and 16C in the radial center, and first and second carriers 38 described later between the offset through holes 14B and 16B. , 40 are provided with carrier pin through holes 14D, 16D through which the carrier pin 38P passes.

  More specifically, a first eccentric part bearing 34 composed of rollers is provided on the outer periphery of the first eccentric part 20, and the first eccentric part 20 is inserted through an offset through hole 14 </ b> B penetrating the first external gear 14. One external gear 14 is incorporated. On the outer periphery of the second eccentric portion 22 of each crankshaft 18, a second eccentric portion bearing 36 composed of a roller is provided, and the second eccentric portion bearing 36 penetrating the second external gear 16 is provided through the second through-hole 16 </ b> B. An external gear 16 is incorporated. As a result, the first eccentric portion 20 on the three crankshafts 18 rotates in synchronization with each other, thereby swinging the first external gear 14, and similarly, the second eccentric portion on the three crankshafts 18. The second external gear 16 can be swung by rotating 22 synchronously. The eccentric phase difference between the first external gear 14 and the second external gear 16 is 180 degrees (in response to the eccentric phase difference between the first eccentric portion 20 and the second eccentric portion 22). The manufacturing method of the first and second external gears 14 and 16 will be described in detail later.

  First and second carriers 38 and 40 are disposed on both axial sides of the first and second external gears 14 and 16. Each of the crankshafts 18 is connected to the first and second carriers 38, 44 through the first and second crankshaft bearings 44 and 46 (bearings that support the crankshaft 18) in the first and second bearing arrangement portions 19 and 21, respectively. 40. The first and second crankshaft bearings 44 and 46 have inner rings 44A and 46A, outer rings 44B and 46B, and tapered rollers 44C and 46C, respectively.

  The first and second carriers 38 and 40 are supported by the casing 52 via a pair of angular ball bearings 48 and 50. The first and second carriers 38 and 40 protrude integrally from the first carrier 38 and pass through the carrier pin through holes 14D and 16D of the first and second external gears 14 and 16 (free fitting). Are connected and integrated by bolts 53 and the like via carrier pins 38P.

  The first and second external gears 14 and 16 are in mesh with the internal gear 12. In this embodiment, the internal gear 12 is an internal gear main body 12A integrated with the casing 52, and an external pin 12B that is rotatably incorporated in the internal gear main body 12A and constitutes internal teeth of the internal gear 12. It consists of and. The number of teeth of the internal gear 12 (the number of external pins 12B) is slightly larger (only 1 in this example) than the number of teeth of the first and second external gears 14 and 16.

  In the present embodiment, a first arm (not shown) of the robot is connected to the casing 52 via a bolt (only the bolt hole 52A is shown), and the first carrier 38 is connected via a bolt (only the tap hole 38B is shown). The second arms (not shown) of the robot are connected to each other. Reference numeral 61 denotes an oil seal.

  Next, the operation of the eccentric oscillating speed reduction device 10 will be described.

  When a motor (not shown) rotates, the input gear 32 formed at the tip of the input shaft 26 rotates. Since the input gear 32 meshes with the three crankshaft gears 30 at the same time, the rotation of the input gear 32 causes the three crankshaft gears 30 to rotate synchronously at the same rotational speed in the same direction.

  Each crankshaft gear 30 is connected to the crankshaft 18 via a fitting hole 30p of the crankshaft gear 30 and a fitting of the torque input portion 70 of the crankshaft 18. Therefore, the three crankshafts 18 are synchronously rotated at the same rotational speed in the same direction while being decelerated to the gear ratio of the input gear 32 and the crankshaft gear 30. As a result, the three first eccentric portions 20 formed at the same position in the axial direction of each crankshaft 18 rotate synchronously to swing the first external gear 14 and the shaft of each crankshaft 18 The three second eccentric portions 22 formed at the same position in the direction rotate in synchronization with each other to swing the second external gear 16.

  Since the first and second external gears 14 and 16 are internally meshed with the internal gear 12, each time the first and second external gears 14 and 16 swing once, the first The second external gears 14 and 16 are out of phase (rotated) in the circumferential direction with respect to the internal gear 12 by a difference in the number of teeth (one tooth in this embodiment). The rotation components of the first and second external gears 14 and 16 are synchronized with the rotations of the crankshafts (rotations of the external gears) via the offset through holes 14B and 16B of the first and second external gears 14 and 16, respectively. The rotation synchronizing member) 18 is transmitted to the first and second carriers 38, 40 as revolutions around the axis O1 of the internal gear 12. Since the first and second carriers 38 and 40 are connected to each other via a carrier pin 38P and a bolt 53 integrated with the first carrier 38, the first and second carriers 38 and 40 are eventually connected to the casing 52 by the rotation of the input shaft 26. The second arm connected to the first carrier 38 can be rotated relative to the first arm.

  Here, the operation relating to the crankshaft 18 and the first and second external gears 14 and 16 will be described in detail together with the description of the respective manufacturing methods.

  In the eccentric oscillating speed reducing device 10, the first and second external gears 14 and 16 and the internal gear 12 are smoothly meshed, and the offset through holes of the first and second external gears 14 and 16 are engaged. It is necessary to smoothly extract the relative rotation between the first and second external gears 14 and 16 and the internal gear 12 via 14B and 16B. For this purpose, the first and second external gears 14 and 16 must be stably swung by the rotation of the crankshaft 18. In particular, as in this embodiment, a so-called sorting type (internal gear and an external gear internally engaged with the internal gear, and a position offset by a predetermined amount from the axis of the internal gear) Further, in the eccentric oscillating speed reducer 10 of the type including a plurality of crankshafts for oscillating external gears, the first and second external gears 14 and 16 of each crankshaft 18 are further provided. It is also necessary that the phases for swinging are accurately aligned.

  Therefore, conventionally, the crankshaft 18 and the first and second external gears 14 and 16 are required to have sufficient hardness and to be finished with high dimensional accuracy. Therefore, conventionally, the materials of the crankshaft 18 and the first and second external gears 14 and 16 are subjected to a process of forming a necessary shape, and then the crankshaft 18 or the first and second external gears 14 and 16 are formed. The entire material was subjected to heat treatment by carburizing and quenching so that each material was given sufficient hardness.

  However, when heat treatment by carburizing / quenching is performed, heat treatment distortion inevitably increases at the end of quenching, making it difficult to ensure a high degree of dimensional accuracy. In other words, the finishing of the crankshaft 18 and the first and second external gears 14 and 16 must be performed on a material that is very hard and has a large heat treatment distortion. There was a problem of cost and time.

  Therefore, in this embodiment, the manufacturing method of “carburizing and quenching the entire material”, which has been conventionally performed for the crankshaft 18 and the first and second external gears 14 and 16, is drastically changed. By revising it and introducing partial induction hardening treatment, while maintaining the strength (hardness) required for the crankshaft 18 and the first and second external gears 14 and 16, the respective finishing costs can be reduced. , So as to shorten the processing time.

  The manufacturing method of the crankshaft 18 will be described with reference to FIG.

  In this embodiment, first, the material of the crankshaft 18 is processed by cutting to form the first and second eccentric parts 20 and 22 of the crankshaft 18 as shown in the upper left of FIG. 2 (step A1). ), A connecting portion 23 is formed between the first eccentric portion 20 and the second eccentric portion 22 (step A2), and the first and second crankshaft bearings 44 and 46 that support the crankshaft 18 are disposed. 1 and 2nd bearing arrangement | positioning parts 19 and 21 are formed (process A3), and the torque input part 70 is further formed (process A4: above, pre-processing process A). Thereafter, as shown in the lower part of FIG. 2, the entire crankshaft 18 (first and second eccentric parts 20 and 22, connection part 23, first and second bearing arrangement parts 19 and 21, and torque input part 70 are arranged. Carburizing treatment is performed on the entire crankshaft 18 including all (step B1). In addition, about the torque input part 70, although carburizing process is performed in this embodiment, it does not necessarily need to perform a carburizing process depending on a structure (rather, a carburizing process may be performed depending on a structure). . For example, a carburizing process is not necessary for the tap hole (torque input part) in the case of adopting a torque input structure in which a tap hole is formed on the end face of the crankshaft and a gear or a pulley is fixed to the tap hole. Rather, it is better to have a carbon-proof treatment. Further, for example, it is preferable that the screw portion in the case where the screw portion is formed on the outer periphery of the crankshaft and the bearing nut is fixed, be subjected to the carbon-proof treatment.

  As a torque input structure, when the key shaft is provided with a hollow crankshaft, the key groove (torque input portion) may be subjected to a carbon-proof treatment, but in the case of a key groove, a solid shaft The shaft end face may be subjected to a carburizing treatment, and the hollow hole and the keyway may be machined after the carburizing treatment (that is, the machining such as the above steps A1 to A4 for forming the main shape of the crankshaft is not necessarily all Need not be performed in the “pre-processing step” of the carburizing process, and the order is not particularly limited). Then, after slow cooling in the carburized furnace (step B2), the first and second eccentric parts 20 and 22 are subjected to induction hardening, and the first and second eccentric parts 20 and 22 The hardness is set to be higher than the hardness of the first and second bearing arrangement portions 19 and 21 (step B3). Thereafter, tempering is performed to increase toughness (step B4).

  Step A1 for forming the first and second eccentric portions 20, 22; Step A2 for forming the connecting portion 23; Step A3 for forming the first and second bearing arrangement portions 19, 21; and the torque input portion 70 are formed. In the step A4, a known forming method can be adopted as appropriate, but in this embodiment, the forming is performed by cutting using a lathe, for example.

  In other words, the series of heat treatments related to the process B (B1 to B4), in other words, the hardness of the first and second eccentric parts 20 and 22 (the induction hardening process) is performed on the crankshaft 18 according to the present embodiment. This is a step of making the hardness higher than the hardness of the first and second bearing arrangement portions 19 and 21. In addition, the series of heat treatments related to the process B (B1 to B4) is more effective in heat treatment distortion than the case where the first and second bearing arrangement portions 19 and 21 are carburized and quenched on the entire crankshaft 18. It is also a process of keeping it small.

  More specifically, in the process B1 related to the carburizing process, the first and second eccentric parts 20 and 22, the connection part 23, the first and second bearing arrangement parts 19 and 21, and the torque input part 70 are formed. The material for the crankshaft 18 is placed in a carburizing furnace, heated in a carbon-containing gas atmosphere (time t1 to t2), and kept at a high temperature (time t2 to t3). In the present embodiment, for example, the temperature is held at about 800 ° C. to 1000 ° C. for about 150 minutes to 450 minutes. The holding temperature and holding time are not particularly limited, and may be set as appropriate according to the size of the material and the required carburization depth. In this embodiment, after that, the temperature is slightly lowered and held for a predetermined time (time t3 to t5). However, the processing at the time t3 to t5 may not be performed. By the above processing, carbon is included in the surface layer portion of the material of the crankshaft 18.

  By this carburizing treatment, carbon can be diffused on the surface of the material up to a carbon concentration capable of forming a martensite structure. That is, when quenching is performed here, the entire structure of the material can be martensite, but this makes it impossible to differentiate the hardness between the parts of the eccentric body axis. Therefore, in this embodiment, after carburizing treatment, the furnace is cooled (slow cooling is performed in the carburizing furnace in which the carburizing treatment is performed) (step B2: times t5 to t6). That is, the furnace is intentionally cooled here to avoid martensite of the structure of the crankshaft 18.

  In the furnace cooling of the process B2, the material of the crankshaft 18 is kept in the furnace even after the heating of the carburizing furnace is finished, and the cooling is performed slowly according to the cooling rate of the furnace. The cooling rate of the furnace cooling is not particularly limited as long as it is a cooling rate that avoids the formation of martensite in the structure, and is usually 30 ° C. to 100 ° C./hour. In this embodiment, the furnace is cooled in the carburized furnace. However, the present invention is not limited to this, and avoids martensite of the structure or at a rate slower than 100 ° C./hour. If it is cooled, it may be cooled by other than a carburizing furnace.

  Next, the material of the crankshaft 18 that has been cooled by the furnace is taken out from the carburizing furnace, and induction hardening is performed only on the first and second eccentric parts 20 and 22 in step B3. Specifically, electromagnetic induction by high-frequency electromagnetic waves is caused in the first and second eccentric parts 20 and 22, the surface is heated (time t11 to t12), and the state is maintained (time t12 to t13). The holding temperature and holding time are not particularly limited, and may be set as appropriate according to the size of the material of the crankshaft 18, the required hardness, the required curing depth, and the like. In the present embodiment, for example, the heating is performed at a temperature slightly lower than that during carburizing. Thereafter, quenching is performed after quenching (in this embodiment, water quenching is performed: times t13 to t14). Through the above processing, the surface layer structure of the first and second eccentric parts 20 and 22 is martensitic.

  Next, tempering is performed in step B4 (time t21 to t24). Although the tempering temperature is not particularly limited, in the present embodiment, for example, the temperature is about 150 ° C. to 300 ° C.

  When the furnace is cooled (slow cooling), the carbon tends to diffuse into the interior, resulting in a decrease in the carbon concentration or an increase in the crystal size, so that the hardness is difficult to increase. On the other hand, the surface layer structure of the first and second eccentric parts 20 and 22 can be martensite by induction hardening with rapid cooling (step B3). Thereby, about the 1st, 2nd bearing arrangement parts 19 and 21, the connection part 23, and the torque input part 70, about the 1st and 2nd eccentric parts 20 and 22, it is required, suppressing the increase in heat processing distortion. Hardness can be ensured reliably. In other words, in this embodiment, instead of quenching the entire material and imparting hardness to the entire material as in carburizing / quenching processing, the hardness as in the first and second eccentric portions 20 and 22 is used. By subjecting the necessary parts to induction hardening, a partial hardness is given, and a “hardness difference” is intentionally generated in the single crankshaft 18.

  In addition, when performing the carburizing process, the slow cooling process, and the induction hardening process of the first and second eccentric parts 20 and 22, the hardness of the surface of the first and second eccentric parts 20 and 22 is the first and second eccentric parts 20 and 22. The Rockwell hardness HRC may be 10 points or more higher than the hardness of the central portions in the radial direction of the two eccentric portions 20 and 22. Thereby, securing of the strength (toughness) of the crankshaft 18 as a whole and securing of surface hardness at the first and second eccentric portions 20 and 22 can both be achieved.

  Next, the process proceeds to finishing process C. That is, the first and second eccentric portions 20 and 22 are thereafter subjected to finishing (step C1). In this embodiment, in order to ensure the coaxiality with the first and second eccentric parts 20 and 22, the first and second bearing arrangement parts 19 and 21 are also finished (step C2). Yes. Since the material of the first and second bearing arrangement portions 19 and 21 is not hard and the heat treatment distortion is small, the “cutting allowance” in the finishing process (step C2) is also small. Therefore, even if the finishing process (step C2) is performed, the finishing process itself is low-cost and simple, and the processing time can be shortened. However, for the first and second bearing arrangement portions 19 and 21, the finishing process (step C2) itself may be omitted (not only the induction hardening process is omitted). In particular, when the first and second crankshaft bearings 44 and 46 having the inner rings 44A and 46A are provided to support the crankshaft 18 as in the present embodiment, the first and second bearing arrangement portions are provided. 19 and 21 do not require so high dimensional accuracy. Actually, since this type of eccentric oscillating speed reducer is often provided with bearings (first and second crankshaft bearings 44 and 46) having inner rings, finishing (step C2). Can often be omitted.

  In the present embodiment, the hardness difference between the first and second eccentric portions 20 and 22 and the first and second bearing arrangement portions 19 and 21 is induction-hardened with respect to the first and second eccentric portions 20 and 22. However, the first and second bearing arrangement portions 19 and 21 are also slightly hardened due to the influence of the induction hardening process on the first and second eccentric portions 20 and 22. Sometimes. However, this phenomenon can be tolerated. In short, the first and second eccentric parts 20 and 22 are actively subjected to induction hardening, and the first and second bearing arrangement parts 19 and 21 are not actively subjected to induction hardening. If it does, the hardness difference of both parts will arise only by it. Practically, it is sufficient if the hardness of the first and second eccentric portions 20 and 22 can be maintained at a Rockwell hardness HRC higher than that of the first and second bearing arrangement portions 19 and 21 by, for example, 10 points or more. The specific process of how to obtain the hardness difference in which part is not particularly limited. For example, in the present embodiment, the entire crankshaft 18 including the first and second eccentric parts 20 and 22, the connection part 23, the first and second bearing arrangement parts 19 and 21, and the torque input part 70 is carburized. However, as already described, for example, the torque input unit 70 is not necessarily required to be carburized, and may be preferably subjected to a carburizing process.

  In the present embodiment, the induction hardening process is not performed on the connecting portion 23 of the crankshaft 18. Therefore, the connection portion 23 has a lower hardness than the first and second eccentric portions 20 and 22 after the induction hardening process (for example, a Rockwell hardness HRC is 10 points or more lower). The connection portion 23 is not actively subjected to induction hardening, but when the induction hardening is performed on the first and second eccentric portions 20 and 22 located on both sides, the influence is not affected. In response, a phenomenon of slight quenching may occur. However, it is not necessary to actively avoid this phenomenon (as a result, the hardness of the connecting portion 23 may not be substantially lower than the hardness of the first and second eccentric portions 20 and 22). .

  In the present embodiment, the step of finishing the connecting portion 23 is omitted. In this embodiment, the connection portion 23 is not originally required to have high-accuracy dimensional control, and since induction hardening is not performed, the heat treatment distortion is not large. Therefore, even if the finishing process of the connection portion 23 is omitted. There is no particular problem.

  The torque input unit 70 of the crankshaft 18 may be subjected to induction hardening in consideration of the torque transmitted by the eccentric oscillating speed reduction device 10, the shape of the torque input unit 70, the allowable backlash amount, and the like. Good or not. For example, when the torque input unit 70 is configured by a key or a tapped hole connected to a drive source side shaft (for example, a motor shaft), the torque input unit 70 does not perform induction hardening processing including the outer periphery. It's okay. When the induction hardening process is not performed on the torque input unit 70, not only the process can be omitted, but also the torque input unit 70 can have an appropriate “softness”. The fitting with the fitting hole 30p becomes better, and the merit that noise is reduced is obtained. In particular, in the case of this embodiment, because of the structure in which three crankshaft gears 30 are simultaneously meshed with one input gear 32, noise due to meshing interference is likely to occur. The noise reduction effect due to the improved familiarity between the torque input portion 70 and the fitting hole 30p of the crankshaft gear 30 is great. Further, when the induction hardening process is not performed on the torque input unit 70, the heat treatment distortion is small, so that the finishing process can often be omitted. Of course, finishing may be performed to ensure a higher degree of dimensional accuracy, but even in the case of finishing, the material is relatively soft, so the cost of finishing can be reduced, Processing time can also be shortened.

  On the other hand, when the torque input unit 70 is configured by a polygon or a spline for mounting a gear as in this embodiment, it may be better to perform induction hardening. Note that when the induction hardening process is performed on the torque input unit 70, heat treatment distortion is greatly generated, and therefore it is preferable to perform a finishing process. Thereby, it is possible to obtain a configuration having high strength (hardness) and high dimensional accuracy.

  In the above-described embodiment, the connecting portion 23 between the first eccentric portion 20 and the second eccentric portion 22 has only a function of ensuring a space between the first eccentric portion 20 and the second eccentric portion 22. In particular, no induction hardening was performed. However, although not shown in the drawings, depending on the eccentric oscillating speed reduction device, the crankshaft gear 30 is not disposed at the axially outer position of the second carrier 40 as in the present embodiment, but the first eccentric portion (20). The crankshaft gear (30) may be disposed at the connection portion (23) between the first eccentric portion (22) and the second eccentric portion (22), and torque may be input to the crankshaft (18) at this axial position. In short, the connection part (23) may be configured to double as the torque input part (70). In this structure, since the twist of the crankshaft (18) reaches the first and second external gears (14, 16) evenly, the eccentric phases of the first and second external gears (14, 16) are more synchronized. There is an advantage that it is easy to take accurately.

  In the eccentric oscillating speed reducer having such a configuration, after the step of forming the gear as the torque input portion at the connecting portion, a step of subjecting the tooth portion of the gear to induction hardening treatment may be provided. . In this case, a finishing process may be further performed. After all, this manufacturing method is “the induction portion and the torque input portion are subjected to induction hardening, and the hardness of both the eccentric portion and the torque input portion is higher than the hardness of the bearing arrangement portion where the crankshaft bearing is arranged. It can be understood as “a manufacturing method that forms a high state”.

  With the above configuration (manufacturing method), while maintaining high hardness of the first and second eccentric portions 20 and 22 (maintaining the hardness necessary for the crankshaft 18), as a result, finishing is easier, In addition, it is possible to obtain a low-cost crankshaft 18 (and thus the eccentric oscillating speed reduction device 10). The cost reduction effect of the crankshaft 18 is particularly noticeable when the eccentric oscillating speed reducer 10 is a distributed type eccentric oscillating speed reducer having a plurality of crankshafts 18 as described above. .

  The basic gist of the present invention can also be applied to the manufacturing method of the first and second external gears 14 and 16.

  With reference to FIG. 3, the structure and manufacturing method of the 1st, 2nd external gears 14 and 16 are demonstrated.

  As shown in the upper left of FIG. 3, the manufacturing method of the first and second external gears 14 and 16 in the present embodiment includes the first and second external gears 14 and 14 by cutting as the pre-processing step D. The process of forming 16 tooth portions 14A, 16A (process D1), and the rotation of the first and second external gears 14, 16 at positions offset from the centers of the first and second external gears 14, 16 The center through hole is formed at the center of the first and second external gears 14 and 16 and the step of forming the offset through holes 14B and 16B of the rotation synchronizing member (the crankshaft 18 in the above embodiment) synchronized with the first and second external gears 14 and 16. A step of forming 14C and 16C (step D3). In this embodiment, a step (step D4) of forming carrier pin through holes 14D and 16D through which the carrier pin 38P connecting the first and second carriers 38 and 40 passes is further added. In addition, the order of this pre-processing process D (D1-D4) may not be this order.

  Thereafter, as shown in the lower part of FIG. 3, a process (process E <b> 1) for carburizing the entire first and second external gears 14 and 16 is performed. Then, induction hardening is applied to the tooth portions 14A, 16A and the offset through holes 14B, 16B, and the periphery (specifically, the inner periphery) of the tooth portions 14A, 16A (specifically, tooth surfaces) and the offset through holes 14B, 16B. The step (step E3) is performed to make the hardness of the surface) higher than the hardness of any part other than the tooth portions 14A and 16A and the offset through holes 14B and 16B of the first and second external gears 14 and 16. . Specifically, in this embodiment, the hardness around the tooth portions 14A and 16A and the offset through holes 14B and 16B is set higher than the hardness around the center through holes 14C and 16C and the carrier pin through holes 14D and 16D. It is high. In addition, also in the case of the 1st, 2nd external gears 14 and 16, tempering is carried out after that and toughness is improved (process E4).

  The series of qualitative heat treatment steps E (E1 to E4) are substantially the same as those in the case of the crankshaft 18 although there are specific differences in temperature, treatment time, and the like. Only the time code is attached, and duplicate explanation is omitted.

  In this embodiment, induction hardening is performed only on the periphery of the tooth portions 14A and 16A and the offset through holes 14B and 16B. The induction hardening process is not performed around the central through holes 14C, 16C and the carrier pin through holes 14D, 16D of the first and second external gears 14, 16 (omitted). Therefore, the hardness of the periphery (inner peripheral surface) of the tooth portions (tooth surfaces) 14A and 16A and the offset through holes 14B and 16B of the first and second external gears 14 and 16 is the center through holes 14C and 16C and the carrier pin. It becomes higher than the hardness around the through holes 14D and 16D (for example, 10 points or more in Rockwell hardness HRC). In the case of this embodiment, the peripheral portions (inner peripheral surfaces) of the tooth portions (tooth surfaces) 14A and 16A and the offset through holes 14B and 16B are finished (step F), but the central through holes 14C and 16C. Also, the periphery of the carrier pin through holes 14D and 16D is not subjected to finishing. This is because the periphery of the central through-holes 14C and 16C and the carrier pin through-holes 14D and 16D is not induction-hardened, so that heat treatment distortion is small, and high functional dimensional accuracy is not required. This is because there is no particular problem even if it is not performed.

  However, it is not prohibited to perform the finishing process (step F) on the central through holes 14C and 16C or the carrier pin through holes 14D and 16D. For example, when the control wire harness is passed through the central through holes 14C and 16C, and when it is desired to avoid damage to the wire harness as much as possible, the central through holes 14C and 16C may be finished. . Even in this case, the periphery of the central through-holes 14C and 16C has low hardness and small heat treatment strain (since the machining allowance is small), the processing is easy and the processing time can be shortened.

  The first and second external gears 14 and 16 of the eccentric oscillating speed reducer 10 have a large difference in internal stress generated in each part of the first and second external gears 14 and 16, and the internal The stress constantly changes as the eccentric phase changes. Therefore, coupled with the large number of meshing points, rolling points, or sliding points, resonance may occur in the external gear. Since the external gear according to the present invention includes a portion having a high hardness and a portion having a low hardness, resonance is further suppressed and an effect of suppressing an increase in vibration and noise can be obtained.

  In addition, when the present invention is applied to the distribution type eccentric oscillating speed reducer as described above, many remarkable effects can be obtained. There is also known a so-called center crank type eccentric oscillating speed reducer having one crankshaft at the gear shaft center position. This one crankshaft penetrates the central through hole in the radial center of the external gear, and the external gear is swung through the central through hole. The present invention can be similarly applied to the manufacture of the crankshaft and the external gear of such a center crank type eccentric oscillating speed reducer.

  When manufacturing the external gear of the center crank type eccentric oscillating speed reducer, in addition to the “tooth portion” and “the offset through hole of the rotation synchronizing member synchronized with the rotation of the external gear”, the crankshaft It is preferable to subject the central through hole penetrating at the center position in the radial direction to induction hardening.

DESCRIPTION OF SYMBOLS 10 ... Eccentric oscillation type reduction gear 12 ... Internal gear 14, 16 ... 1st, 2nd external gear 18 ... Crankshaft 19, 21 ... 1st, 2nd bearing arrangement part 20, 22 ... 1st, 2nd Eccentric part 30 ... Crankshaft gear 70 ... Torque input part

Claims (9)

An internal gear, an external gear meshing with the internal gear, and a crankshaft for swinging the external gear, wherein the crankshaft includes a plurality of eccentric portions, and the eccentric portion and the eccentric portion. An eccentric part bearing on the outer periphery of the eccentric part, comprising: a connecting part provided therebetween; a bearing arrangement part in which a bearing supporting the crankshaft is arranged; and a torque input part for receiving torque from the input side A manufacturing method of a crankshaft of an eccentric oscillating speed reducer in which the external gear is incorporated via
Forming an eccentric portion of the front Kifuku number, a step of forming the connecting portion, forming a pre-Symbol axis power distribution part, forming said torque input part,
A step of carburizing the plurality of eccentric parts, the connection part, and the bearing arrangement part;
Subjecting the plurality of eccentric portions to induction hardening, and making the hardness of the plurality of eccentric portions higher than the hardness of the bearing arrangement portion;
A step of performing a finishing process after the induction hardening process on the plurality of eccentric parts,
And a step of finishing the bearing arrangement portion . A method of manufacturing a crankshaft of an eccentric oscillating speed reducer. In claim 1,
In the step of performing the carburizing process, the carburizing process is also performed on the torque input unit. A method of manufacturing a crankshaft of an eccentric rocking type reduction gear. In claim 1 or 2,
The connecting part also maintains a lower hardness than the eccentric part after the induction hardening process. A method of manufacturing a crankshaft of an eccentric oscillating speed reducer. In any one of Claims 1-3,
Before SL connections, manufacturing method of a crank shaft of the eccentric oscillating type reduction gear, characterized in that omit the step of performing finishing. In any one of Claims 1-4 ,
The torque input section also maintains a lower hardness than the eccentric section after the induction hardening process. A method of manufacturing a crankshaft of an eccentric oscillating speed reducer. In any one of Claims 1-5 ,
After the said carburizing process, it anneals in the furnace which performed the said carburizing process, and performs the said induction hardening process. The manufacturing method of the crankshaft of the eccentric rocking | swiveling type speed reducer characterized by the above-mentioned. In claim 1,
Forming a gear as the torque input portion in the connection portion;
And a step of subjecting the tooth portion of the gear to an induction hardening process. A method of manufacturing a crankshaft of an eccentric oscillating speed reducer. A manufacturing method of an external gear of an eccentric oscillating speed reducer,
Forming a tooth portion of the external gear;
Forming an offset through hole of a rotation synchronizing member synchronized with the rotation of the external gear at a position offset from the center of the external gear;
Forming a central through hole at the center of the external gear;
A step of carburizing the entire external gear;
The tooth portion and the offset through-hole are subjected to induction hardening treatment, and the hardness of the tooth surface of the tooth portion and the inner peripheral surface of the offset through-hole is set to any part other than the inner peripheral surface of the tooth surface and the offset through-hole. A method of manufacturing an external gear of an eccentric oscillating speed reducer, comprising a step of making the hardness higher than the hardness. In claim 8 ,
The eccentric oscillating speed reducer is a center crank type eccentric oscillating speed reducer in which a crankshaft having an eccentric portion for oscillating the external gear penetrates the central through hole of the external gear. There,
A method of manufacturing an external gear of an eccentric oscillation type reduction gear, wherein the inner peripheral surface of the central through hole is also subjected to induction hardening.

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