Gear arrangement and reduction gear

Abstract

Provided are a gear device and a speed reducer. The gear device includes a first gear and a second gear that mesh with each other. Machining marks (50a) are formed on each tooth surface of the first gear and the second gear. The machining marks (50a) of the first gear and the machining marks of the second gear extend in directions that cross each other when the first gear and the second gear mesh.

Description

Technical Field

[0001] This invention relates to gear mechanisms and speed reducers. Background Technology

[0002] In recent years, industrial robots and other equipment have been used more frequently in collaborative spaces where they work in conjunction with operators. In such equipment, speed reducers are used to slow the rotation of drive sources such as motors. Therefore, it is important to suppress the noise generated in the speed reducers used in such equipment to a level that is imperceptible to the operator.

[0003] The speed reducer includes a main reduction mechanism and an input-side power transmission mechanism (transmission gear set) for transmitting power to the reduction mechanism. The input-side power transmission mechanism includes an input gear connected to a drive source such as a motor and a transmission gear for transmitting power to the main speed reducer. The input gear and the transmission gear mesh with each other. The gears in the input-side power transmission mechanism sometimes rotate at relatively high speeds, making this mechanism a potential source of noise during operation.

[0004] Therefore, as a countermeasure against noise generated from the power transmission mechanism, there is a known gear device that reduces the noise generated by improving the meshing part of the gears (see Patent Document 1).

[0005] The gear assembly described in Patent Document 1 has grinding marks extending along the tooth profile direction formed on the tooth surfaces of the meshing first and second gears. In this gear assembly, since the grinding marks of the two gears extend along the tooth profile direction, the sliding direction accompanying the meshing rotation of the two gears is consistent with the direction of the grinding marks. Therefore, the generation of noise associated with sliding can be suppressed.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-214941 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, in the gear device described in Patent Document 1, the grinding marks of both the first and second gears extend in the sliding direction of the tooth surface, making it difficult to maintain an oil film for lubricating the sliding tooth surface. Consequently, under certain usage conditions, the frictional resistance at the sliding contact portion of the tooth surface increases, making it difficult to adequately suppress noise generation and tooth surface wear.

[0011] The present invention provides a gear device and reducer that can maintain an oil film on the meshing tooth surfaces and can suppress noise generation and extend product life.

[0012] Solution for solving the problem

[0013] A gear device according to one embodiment of the present invention includes a first gear and a second gear that mesh with each other. Machining marks are formed on the tooth surfaces of both the first gear and the second gear. When the first gear meshes with the second gear, the machining marks on the first gear and the second gear extend in mutually intersecting directions.

[0014] In this gear assembly, the machining marks formed on the tooth surfaces of the first and second gears extend in mutually intersecting directions. Therefore, when the tooth surfaces of the first and second gears slide into contact with each other as they rotate, the oil film that is to be peeled off along the machining mark of one gear is left by the edge portion (the edge portion in the direction orthogonal to the extending direction) in the width direction of the machining mark of the other gear. Thus, the oil film can be well maintained on the tooth surfaces of both gears.

[0015] Alternatively, when the first gear and the second gear mesh, the machining marks of the first gear and the machining marks of the second gear extend in mutually orthogonal directions.

[0016] In this case, the oil film that is to be peeled off along the machining mark of one gear can be more reliably left by the edge portion (the edge in the direction orthogonal to the extension direction) in the width direction of the machining mark of the other gear.

[0017] Alternatively, the machining marks of at least one of the first gear and the second gear may extend in multiple different directions.

[0018] In this case, the oil film is more likely to remain on the machining marks and can maintain a sufficient oil film on the tooth surface.

[0019] A speed reducer according to one embodiment of the present invention comprises: a housing having internal teeth on its inner circumference; a gear carrier rotatably held in the housing; a crankshaft rotatably supported on the gear carrier, which is subjected to an external rotational force to rotate its eccentric portion; an oscillating gear having external teeth that mesh with the internal teeth in a number fewer than the internal teeth, which is subjected to a rotational force from the eccentric portion of the crankshaft and oscillates to output rotational power to the gear carrier or the housing; and a transmission gear set on the input side, which is composed of a plurality of gear elements whose teeth mesh with each other to transmit rotational power to the crankshaft. Machining marks are formed on the tooth surfaces of at least one pair of meshing gear elements in the transmission gear set. The machining marks of one meshing gear element and the machining marks of the other meshing gear element extend in mutually intersecting directions when the gear elements mesh.

[0020] In the reducer of this structure, at least one pair of meshing gear elements on the input side of the transmission gear set have machining marks formed on their tooth surfaces, with the machining marks of one gear element and the other gear element extending in intersecting directions. Therefore, when the tooth surfaces of the gear elements slide against each other as they rotate, the oil film that would otherwise be peeled off along the machining mark of one gear element is left by the edge portion (the edge portion in the direction orthogonal to the extending direction) in the width direction of the machining mark of the other gear element. Thus, the oil film can be well maintained on the tooth surfaces of the gear elements.

[0021] The effects of the invention

[0022] In a gear assembly according to one embodiment of the present invention, the oil film remains on the machining marks of the teeth of the meshing first and second gears, making it easy to maintain the oil film on each tooth surface. Therefore, with the gear assembly employing the technical solution of the present invention, noise generation can be suppressed and product lifespan extended.

[0023] In a reducer according to one embodiment of the present invention, in at least one pair of meshing gear elements of the transmission gear set on the input side, the oil film remains on the machining marks on each tooth surface, making it easy to maintain the oil film on each tooth surface. Therefore, when a reducer using one embodiment of the present invention is adopted, it is possible to suppress noise generation in the transmission gear set on the input side and extend the product life of the gear elements constituting the transmission gear set on the input side. Attached Figure Description

[0024] Figure 1 This is a side view of an industrial robot equipped with a speed reducer.

[0025] Figure 2 This is a schematic front view of the speed reducer according to the implementation method.

[0026] Figure 3 The reducer in the implementation method is along Figure 2 A cross-sectional view along line III-III.

[0027] Figure 4 This is a partial cross-sectional perspective view of the input gear used in the reducer of the embodiment.

[0028] Figure 5 This is a partial cross-sectional perspective view of the transmission gear used in the reducer of the embodiment.

[0029] Figure 6 It is a graph representing the test results obtained by showing the change in the average coefficient of friction for each surface roughness of the test piece investigating the gear.

[0030] Explanation of reference numerals in the attached figures

[0031] 10. Reducer; 11. Housing; 13A. First gear carrier module (gear carrier); 13B. Second gear carrier module (gear carrier); 14. Crankshaft; 14b. Eccentric part; 15A. First oscillating gear (oscillating gear); 15B. Second oscillating gear (oscillating gear); 15Aa, 15Ba. External gear; 20. Internal gear pin (internal gear); 25. Gear assembly; 30. Input gear (gear element of transmission gear set, first gear); 30a. Tooth; 30as. Tooth surface; 40 (40A, 40B, 40C); Transmission gear (gear element of transmission gear set, second gear); 40a. Tooth; 40as. Tooth surface; 50a, 50b. Machining marks; 60. Transmission gear set. Detailed Implementation

[0032] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0033] Figure 1 This is a side view of an industrial robot 100 that employs the reducer 10 of the embodiment.

[0034] like Figure 1 As shown, the industrial robot 100 is used, for example, for tasks such as component supply and assembly in the manufacture of precision equipment. The industrial robot 100 of this embodiment includes a base 110, a first arm 120, a second arm 130, a working head 140, and an end effector 150.

[0035] The base 110 includes a motor 160 and a reducer 10. The motor 160 is a drive source such as a servo motor. The first arm 120 is connected to the output of the reducer 10.

[0036] The first arm 120 rotates about axis O1. The power of the motor 160 is reduced by the reducer 10 at a predetermined reduction ratio and transmitted to the first arm 120. The second arm 130 is rotatably connected to the front end of the first arm 120.

[0037] The second arm 130 rotates about an axis parallel to axis O1. The second arm 130 rotates using the power of a motor (not shown). A working head 140 is held at the front end of the second arm 130.

[0038] An end effector 150, such as a robotic arm, is mounted on the work head 140. The end effector 150 operates using power from a motor (not shown).

[0039] Figure 2 This is the front view of the reducer 10 when viewed from the input side (the side connected to the motor 160).

[0040] like Figure 2As shown, the reducer 10 includes three transmission gears 40 (40A, 40B, 40C) composed of spur gears and an input gear 30 composed of spur gears. The input gear 30 is connected to the motor 160 (see reference). Figure 1 The output shaft is connected. Both the transmission gear 40 and the input gear 30 are involute gears.

[0041] In this embodiment, the input gear 30 and the transmission gear 40 constitute the transmission gear set 60 on the input side. The input gear 30 and the transmission gear 40 constitute the gear elements of the transmission gear set 60.

[0042] In addition, the input gear 30 and the transmission gear 40 constitute a meshing gear device 25 (see reference). Figure 4 , Figure 5 ).

[0043] In this embodiment, the input gear 30 constitutes the first gear of the gear device 25, and the transmission gear 40 constitutes the second gear of the gear device 25.

[0044] exist Figure 2 The diagram shows the central axis O1 of the input gear 30 and the central axes C1, C2, and C3 of the three transmission gears 40A, 40B, and 40C. The central axis O1 of the input gear 30 coincides with the central axis O1 of the gear carriers (first gear carrier module 13A and second gear carrier module 13B), which will be described later. Furthermore, the central axis O1 of the input gear 30 also coincides with the central axis O1 of the first arm 120 (see reference). Figure 1 The axis O1 of the rotation center of ) is consistent.

[0045] Three transmission gears 40A, 40B, and 40C are arranged at approximately equal intervals on an imaginary circle centered on the central axis O1 of the input gear 30. The central axes C1, C2, and C3 of each transmission gear 40A, 40B, and 40C coincide with the central axes C1, C2, and C3 of the three crankshafts 14, which will be described later. Each tooth 40a (external tooth) of the three transmission gears 40A, 40B, and 40C meshes with the tooth 30a (external tooth) of the input gear 30.

[0046] The rotation input from motor 160 to input gear 30 is transmitted equally to the three transmission gears 40A, 40B, and 40C as a rotation in the opposite direction to the rotation of input gear 30.

[0047] Figure 3 It is along Figure 2 A cross-sectional view along line III-III.

[0048] like Figure 3 As shown, the reducer 10 includes a cylindrical housing 11, a first gear carrier module 13A, a second gear carrier module 13B, three crankshafts 14, a first oscillating gear 15A, and a second oscillating gear 15B.

[0049] The first gear carrier module 13A and the second gear carrier module 13B are rotatably held on the inner circumference of the housing 11. Three crankshafts 14 are rotatably supported on the first gear carrier module 13A and the second gear carrier module 13B. The first oscillating gear 15A and the second oscillating gear 15B rotate together with the two eccentric portions 14b of each crankshaft 14.

[0050] In this embodiment, the housing 11 is fixed to the base 110 of the industrial robot 100. The first gear carrier module 13A and the second gear carrier module 13B constitute a gear carrier that functions as an output rotating body. The first oscillating gear 15A and the second oscillating gear 15B constitute oscillating gears that oscillate and rotate due to rotational force received from the eccentric portion 14b of the crankshaft 14.

[0051] The first gear carrier module 13A has a perforated circular plate-shaped base plate portion 13Aa and a plurality of support portions 13Ab extending from the end face of the base plate portion 13Aa toward the second gear carrier module 13B.

[0052] The second gear carrier module 13B is formed as an open circular plate. The first gear carrier module 13A is assembled with the second gear carrier module 13B with the end face of the support portion 13Ab in contact with the end face of the second gear carrier module 13B. Each support portion 13Ab is fastened to the second gear carrier module 13B using bolts 16.

[0053] In addition, the second gear carrier module 13B is provided with a positioning pin 17, which is used to position the second gear carrier module 13B relative to each support portion 13Ab before fastening with bolts 16.

[0054] An axial gap (separation space) is ensured between the base plate portion 13Aa of the first gear carrier module 13A and the second gear carrier module 13B. The first oscillating gear 15A and the second oscillating gear 15B are arranged in this gap (separation space).

[0055] Furthermore, clearance holes 19 are formed in the first oscillating gear 15A and the second oscillating gear 15B respectively, for each support portion 13Ab of the first gear carrier module 13A to pass through. The clearance holes 19 are formed to be sufficiently large compared to the outer shape of the support portion 13Ab, so as to avoid the support portion 13Ab from obstructing the rotational movement of the first oscillating gear 15A and the second oscillating gear 15B.

[0056] The shell 11 has a cylindrical shell body 11a and a flange 11b that protrudes radially outward from the outer periphery of the shell body 11a. The shell body 11a and the flange 11b are integrally formed, for example, by casting.

[0057] The housing body 11a is arranged across the outer peripheral surface of the base plate portion 13Aa of the first gear carrier module 13A and the outer peripheral surface of the second gear carrier module 13B. The base plate portion 13Aa of the first gear carrier module 13A and the second gear carrier module 13B are rotatably supported on both axial sides of the housing body 11a by means of bearings 12.

[0058] In the housing body 11a, a plurality of pin grooves 18 are formed on the inner peripheral surface of a central region located axially in the center (the region opposite to the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B), extending parallel to the rotation center (central axis O1) of the first and second gear carrier modules 13A and 13B. Each pin groove 18 rotatably accommodates a cylindrical internal toothed pin 20. The plurality of internal toothed pins 20 mounted on the inner peripheral surface (pin groove 18) of the housing body 11a are opposite to the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B.

[0059] In this embodiment, the internal toothed pin 20 installed in the pin groove 18 constitutes the internal teeth of the housing 11.

[0060] The first oscillating gear 15A and the second oscillating gear 15B are formed with an outer diameter slightly smaller than the inner diameter of the housing body 11a. External teeth 15Aa and 15Ba are formed on the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B, respectively, and engage with a plurality of internal toothed pins 20 disposed on the inner peripheral surface of the housing body 11a. The number of teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal toothed pins 20 (pin grooves 18) (for example, one less).

[0061] Three crankshafts 14 are arranged on the same circumference centered on the rotation center (central axis O1) of the first gear carrier module 13A and the second gear carrier module 13B. Each crankshaft 14 is rotatably supported on the first gear carrier module 13A and the second gear carrier module 13B by means of bearings 21.

[0062] Each crankshaft 14 has a pair of shaft support portions 14a arranged axially apart and two eccentric portions 14b disposed between the pair of shaft support portions 14a. At one end of the crankshaft 14 in the axial direction, a gear mounting portion 14c is formed adjacent to the shaft support portion 14a. Each shaft support portion 14a passes through a shaft support hole 13Aa-1 formed in the first gear carrier module 13A (base plate portion 13Aa) and a shaft support hole 13Ba-1 formed in the second gear carrier module 13B. Each shaft support portion 14a is rotatably supported in the shaft support holes 13Aa-1 and 13Ba-1 by means of a bearing 21.

[0063] The gear mounting portion 14c of each crankshaft 14 passes through the shaft support hole 13Ba-1 of the second gear carrier module 13B and protrudes axially outward from the second gear carrier module 13B. Transmission gears 40 (40A, 40B, 40C) are mounted in the gear mounting portion 14c.

[0064] The transmission gears 40 (40A, 40B, 40C) are connected to the gear mounting portion 14c of the crankshaft 14 in a manner that allows them to rotate integrally, for example, by means of spline engagement. In this state, the transmission gears 40 (40A, 40B, 40C) further mesh with the input gear 30.

[0065] The input gear 30 and transmission gears 40 (40A, 40B, 40C) of the transmission gear set 60 constituting the input side are covered from the outside in the axial direction by a cover (not shown). Lubricant is filled in the space enclosed by the housing 11 and the cover. Therefore, the tooth surfaces of the input gear 30 and the transmission gears 40 (40A, 40B, 40C) are lubricated by the lubricant.

[0066] The central axes of the two eccentric portions 14b of the crankshaft 14 are eccentric relative to the central axis of the shaft support portion 14a. In addition, the two eccentric portions 14b are eccentric in such a way that their phases are offset by 180° around the central axis of the shaft support portion 14a.

[0067] Each eccentric portion 14b of the crankshaft 14 passes through the first oscillating gear 15A and the second oscillating gear 15B respectively. Each eccentric portion 14b is rotatably engaged with the support holes 22 formed in the first oscillating gear 15A and the second oscillating gear 15B respectively by means of the eccentric bearing 23 (cylindrical roller bearing).

[0068] In the reducer 10 of this embodiment, when the plurality of crankshafts 14 are subjected to an external force and rotate in one direction, each eccentric portion 14b of the crankshaft 14 rotates in the same direction with a predetermined radius. As a result, the first oscillating gear 15A and the second oscillating gear 15B rotate (oscillate) in the same direction with the same radius as each eccentric portion 14b rotates. At this time, each external tooth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B contacts in meshing manner with a plurality of internal toothed pins 20 held on the inner circumference of the housing body 11a.

[0069] In the reducer 10 of this embodiment, the number of teeth 15Aa and 15Ba of the external teeth of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal tooth pins 20 on the housing body 11a side (for example, one less). Therefore, during the period when the first oscillating gear 15A and the second oscillating gear 15B rotate one revolution with the rotation of the crankshaft 14, the first oscillating gear 15A and the second oscillating gear 15B are subjected to a reaction force in the direction of rotation from the internal tooth pins 20 on the housing body 11a side and rotate on their own axis, and then revolve in the opposite direction of rotation by a predetermined tooth pitch. As a result, the first and second gear carrier modules 13A and 13B, which engage with the first oscillating gear 15A and the second oscillating gear 15B by means of the crankshaft 14, rotate together with the first and second oscillating gears 15A and 15B in the same direction with the same tooth pitch.

[0070] As a result, the rotation of crankshaft 14 is reduced at a predetermined reduction ratio and output as the rotation of the first and second gear carrier modules 13A and 13B. In this embodiment, the first gear carrier module 13A and Figure 1 The first arm 120 is connected as shown. Therefore, the rotation after being reduced by the reducer 10 is output as the rotation of the first arm 120.

[0071] Furthermore, in this embodiment, since the two eccentric portions 14b of the crankshaft 14 are eccentrically offset by 180° around the central axes C1, C2, and C3, the rotation phases of the first oscillating gear 15A and the second oscillating gear 15B are offset by 180°.

[0072] Figure 4 This is a partial sectional perspective view of the input gear 30, which constitutes the first gear of the gear assembly 25.

[0073] like Figure 4 As shown, machining marks 50a are formed on the tooth surfaces 30as of each tooth 30a of the input gear 30. In this specification, "machining mark" refers to a fine machining trace formed on the surface during tooth cutting or grinding. The machining marks 50a on the tooth surfaces 30as of the input gear 30 can be formed, for example, during tooth profile cutting using a gear shaper, gear hobbing machine, or surface grinding using a honing machine. The machining marks 50a on the tooth surfaces 30as of the input gear 30 extend along the tooth profile (from the tooth root towards the tooth tip).

[0074] Figure 5 This is a partial sectional perspective view of the transmission gear 40 that constitutes the second gear of the gear assembly 25.

[0075] like Figure 5As shown, similar to the input gear 30, machining marks 50b are formed on the tooth surfaces 40as of each tooth 40a of the transmission gear 40. As with the input gear 30, the machining marks 50b can be formed during tooth profile cutting using a gear shaper, gear hobbing machine, or surface grinding using a honing machine. The machining marks 50b on the tooth surfaces 40as of the transmission gear 40 extend along the tooth width direction (tooth line direction).

[0076] Therefore, when the input gear 30 and the transmission gear 40 mesh, the machining marks 50a on the tooth surface 30as of the input gear 30 and the machining marks 50b on the tooth surface 40as of the transmission gear 40 extend in mutually orthogonal directions. Furthermore, it is most preferable that the machining marks 50a on the input gear 30 and the machining marks 50b on the transmission gear 40 extend in mutually orthogonal directions, but as long as they intersect, they do not necessarily have to be orthogonal.

[0077] A lubricating oil film is formed on each tooth surface 30as, 40as of the meshing input gear 30 and transmission gear 40. As a result, the sliding resistance associated with the rotation of the input gear 30 and transmission gear 40 in the meshing state is reduced by the lubricating oil film.

[0078] The reducer 10 may operate under various conditions. Therefore, for example, the input gear 30 and the transmission gear 40 may operate under conditions of low surface pressure and high circumferential speed, or high surface pressure and low circumferential speed. Under such operating conditions, the oil film is easily detached from the tooth surfaces 30as and 40as.

[0079] In this respect, in this embodiment, when the input gear 30 and the transmission gear 40 mesh with each other, the machining marks 50a of the input gear 30 and the machining marks 50b of the transmission gear 40 extend in mutually intersecting directions, thereby suppressing the oil film from peeling off from each tooth surface 30as, 40as.

[0080] Specifically, when the tooth surfaces 30as and 40as of the input gear 30 and the transmission gear 40 slide into contact with each other as they rotate, the oil film may attempt to peel off along the machining marks 50a (50b) of one gear. However, even if the oil film exhibits such behavior, it can be retained by the edge portion (the edge portion in the direction orthogonal to the extending direction) in the width direction of the machining mark 50b (50a) of the other gear. Therefore, the oil film can be well maintained on each tooth surface 30as and 40as of the input gear 30 and the transmission gear 40.

[0081] Furthermore, the surface roughness of each tooth surface 30as and 40as of the input gear 30 and the transmission gear 40 is set to Ra 0.8 to 0.2 μm. By setting the surface roughness of each tooth surface 30as and 40as that slides in contact with each other within the range of Ra 0.8 to 0.2 μm, it is easier to maintain the oil film on the surface and keep the frictional resistance of the two tooth surfaces 30as and 40as within an appropriate range.

[0082] Figure 6 It is a graph showing the results obtained by investigating the change in the average coefficient of friction for each surface roughness using test pieces of gears.

[0083] In this experiment, the pressing component was pressed against test pieces with varying surface roughness, and the test pieces were rotated at a specified speed. The coefficient of friction was then investigated. The coefficient of friction of the test pieces was measured by changing the rotation speed of the test pieces to 180 rpm, 100 rpm, and 40 rpm.

[0084] like Figure 6 As shown, regardless of the rotation speed, the coefficient of friction can be kept sufficiently low when the surface roughness of the test piece is Ra0.6μm or Ra0.2μm, compared to the comparative example with a surface roughness of Ra0.03μm.

[0085] As described above, in the gear device 25 of this embodiment, the machining marks 50a and 50b on the tooth surfaces 30as and 40as of the meshing input gear 30 (first gear) and transmission gear 40 (second gear) extend in mutually intersecting directions. Therefore, an oil film remains on the machining marks 50a and 50b on the tooth surfaces 30as of the input gear 30 (first gear) and transmission gear 40 (second gear), making it easy to maintain an oil film on each tooth surface 30as and 40as.

[0086] Therefore, when the gear device 25 of this embodiment is adopted, noise generation can be suppressed and product life can be extended.

[0087] In particular, in the gear device 25 of this embodiment, the machining marks 50a and 50b on the tooth surfaces 30as and 40as of the input gear 30 (first gear) and the transmission gear 40 (second gear) extend in a mutually orthogonal manner. Therefore, the oil film that is to be peeled off along the machining mark 50a (50b) of one gear can be efficiently left by the edge portion (the edge portion in the direction orthogonal to the extension direction) in the width direction of the machining mark 50b (50a) of the other gear.

[0088] Furthermore, the reduction mechanism of the reducer 10 in this embodiment is composed of a housing 11, a gear carrier (first gear carrier module 13A and second gear carrier module 13B), a crankshaft 14, and oscillating gears (first oscillating gear 15A and second oscillating gear 15B). The transmission gear set 60 on the input side that transmits power to the reduction mechanism is composed of an input gear 30 as one of the gear elements and a transmission gear 40 as another gear element. The machining marks 50a and 50b formed on the tooth surfaces 30as and 40as of the input gear 30 and the transmission gear 40 extend in mutually intersecting directions. Therefore, the oil film remains on the machining marks 50a and 50b of the tooth surfaces 30as and 40as, making it easy to maintain the oil film on each tooth surface 30as and 40as.

[0089] Therefore, when the reducer 10 of this embodiment is adopted, it is possible to suppress the noise generated in the transmission gear set 60 on the input side and extend the product life of each gear element (input gear 30 and transmission gear 40) constituting the transmission gear set 60 on the input side.

[0090] <Other Implementation Methods>

[0091] In the above embodiment, machining marks 50a and 50b are formed on each tooth surface 30as and 40as of the input gear 30 and the transmission gear 40, respectively, extending in only one direction. However, the machining marks formed on each tooth surface 30as and 40as may also extend in multiple different directions. Specifically, for example, the machining marks may also be grid-like, honeycomb-like, etc.

[0092] In this case, it is also possible to form a grid-like or honeycomb-like machining mark on only one of the two tooth surfaces 30as and 40as, and to form a machining mark on the other in a manner that extends in only one direction.

[0093] In the gear device of this embodiment, since the machining marks of at least one of the tooth surfaces 30as and 40as extend in multiple different directions, the oil film is more likely to remain on the machining marks and maintain a sufficient oil film on the tooth surface.

[0094] Furthermore, the present invention is not limited to the embodiments described above, and various design changes can be made without departing from its spirit. For example, the reducer 10 of the above embodiment has two oscillating gears (first oscillating gear 15A and second oscillating gear 15B), but the number of oscillating gears may be one, or even three or more.

[0095] Furthermore, in the above embodiment, the housing 11 side of the reducer 10 is fixed to the base, and the gear carrier (first gear carrier module 13A and second gear carrier module 13B) rotates as an output rotating body. However, it is also possible to reverse the configuration, fixing the gear carrier side to the base and using the housing 11 side as the output rotating body.

[0096] Furthermore, in the reducer 10 of the above-described embodiment, the input-side transmission gear set 60 consists of an input gear 30 connected to the output shaft of the motor 160 and a transmission gear 40 mounted on the crankshaft 14. However, the structure of the input-side transmission gear set 60 is not limited to this. For example, an intermediate gear may be sandwiched between the input gear and the transmission gear. In this case, at least one meshing gear pair among the input gear, intermediate gear, and transmission gear constituting the transmission gear set can be machined with the same machining marks as in the above-described embodiment.

[0097] Furthermore, in the above embodiment, the reducer 10 is applied to the drive unit of the industrial robot 100, but the application of the reducer 10 is not limited to the drive unit of the industrial robot 100. The reducer 10 can also be applied to the drive units of various other equipment such as machine tools, other than the industrial robot 100.

[0098] Furthermore, in the above embodiment, the input gear 30 and the transmission gear 40 of the reducer 10 constitute the gear device 25 in this embodiment, but the application of the gear device 25 is not limited to the reducer 10. The gear device 25 can also be applied to various devices other than the reducer 10.

[0099] Furthermore, in the embodiments disclosed in this specification, for a structure composed of multiple objects, the multiple objects can be integrated into one unit, and conversely, a structure composed of a single object can be divided into multiple objects. Whether or not they are integrated, as long as the configuration achieves the purpose of the invention, it is acceptable.

Claims

1. A gear mechanism, wherein, The gear mechanism has a first gear and a second gear that mesh with each other. Machining marks are formed on each tooth surface of the first gear and the second gear. When the first gear and the second gear mesh, the machining marks on the first gear and the machining marks on the second gear extend in mutually intersecting directions.

2. The gear device according to claim 1, wherein, When the first gear and the second gear mesh, the machining marks on the first gear and the machining marks on the second gear extend in mutually orthogonal directions.

3. The gear device according to claim 1 or 2, wherein, The machining marks of at least one of the first gear and the second gear extend in multiple different directions.

4. A speed reducer, wherein, This reducer has the following features: The shell has internal teeth on its inner circumference; A gear carrier, which is rotatably held in the housing; A crankshaft, which is rotatably supported on the gear carrier, is subjected to an external rotational force that causes the eccentric portion of the crankshaft to rotate. An oscillating gear, having external teeth that mesh with the internal teeth in fewer numbers than the internal teeth, oscillates and rotates due to a rotational force from the eccentric portion of the crankshaft, outputting rotational output to the gear carrier or the housing; and The input-side transmission gear set consists of multiple gear elements that mesh with each other to transmit rotational power to the crankshaft. Machining marks are formed on the tooth surfaces of at least one pair of meshing gear elements in the transmission gear set. The machining marks of one meshing gear element and the machining marks of the other meshing gear element extend in mutually intersecting directions when the gear elements mesh with each other.

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