阅读说明：本技术 紧固构造和产业机械 (Fastening structure and industrial machine ) 是由 王宏猷 中村江児 增田智彦 赤尾正贵 于 2019-08-08 设计创作，主要内容包括：本发明提供一种紧固构造和产业机械。紧固构造(FS)具有：螺栓(B1、B2、B3)；第1构件(10、20、32、6Y),其具有被螺栓(B1、B2、B3)贯穿了的贯通孔(TH1、TH2、TH3),并且用于承接螺栓(B1、B2、B3)的接触面部(SS1、SS2、SS3)处的维氏硬度是300Hv以上；以及第2构件(6X、31a、10、30),其具有供贯穿了贯通孔(TH1、TH2、TH3)的螺栓(B1、B2、B3)啮合的螺纹孔(SH1、SH2、SH3)。将螺栓(B1、B2、B3)的公称直径设为d〔mm〕,将贯通孔(TH1、TH2、TH3)的深度设为L〔mm〕,螺栓(B1、B2、B3)的松动开始角度成为0.02×L/d<Sup>4</Sup>〔°〕以上。(The invention provides a fastening structure and an industrial machine. The Fastening Structure (FS) comprises: bolts (B1, B2, B3); a 1 st member (10, 20, 32, 6Y) having through holes (TH1, TH2, TH3) through which bolts (B1, B2, B3) pass, and having a Vickers hardness of 300Hv or more at contact surface portions (SS1, SS2, SS3) for receiving the bolts (B1, B2, B3); and a 2 nd member (6X, 31a, 10, 30) having screw holes (SH1, SH3) for engaging bolts (B1, B2, B3) passing through the through holes (TH1, TH2, TH3)2. SH 3). The nominal diameter of bolts (B1, B2, B3) is d [ mm ], the depth of through holes (TH1, TH2, TH3) is L [ mm ], and the loosening start angle of bolts (B1, B2, B3) is 0.02 xL/d 4 And (l) above.)

1. A fastening structure is provided with:

a bolt;

a through hole through which the bolt passes;

a contact surface portion having a Vickers hardness of 300Hv or more and adapted to receive the bolt; and

a support portion for fixing the bolt inserted through the through hole,

in this fastening configuration, the first and second fastening means,

the nominal diameter of the bolt is d, the depth of the through hole is L, and the loosening starting angle of the bolt is 0.02 xL/d⁴The aboveThe nominal diameter of the bolt and the depth of the through hole are in mm, and the loosening start angle of the bolt is in mm.

2. The fastening construction according to claim 1,

assuming that a nominal diameter of the bolt is d, a depth of the through hole is L, and the loosening start angle of the bolt is 0.06 xL/d⁴Hereinafter, the nominal diameter of the bolt and the depth of the through hole are expressed in mm, and the loosening start angle of the bolt is expressed in °.

3. The fastening construction according to claim 1,

the bolt has a nominal diameter d, a depth L of the through hole, and a loosening start angle of 0.03 xL/d⁴In the above, the nominal diameter of the bolt and the depth of the through hole are in mm, and the loosening start angle of the bolt is in ° degrees.

4. The fastening construction according to claim 1,

one of the contact surface portion and the support portion is a speed reducer.

5. The fastening construction according to claim 1,

one of the contact surface portion and the support portion is a 1 st portion of a carrier of a speed reducer,

the other of the contact surface portion and the support portion is a 2 nd portion of a carrier of the speed reducer.

6. An industrial machine, wherein,

the industrial machine is provided with the fastening structure according to any one of claims 1 to 5.

7. A fastening structure is provided with:

a bolt;

a contact surface portion having a Vickers hardness of 300Hv or more and receiving a head portion of the bolt;

a through hole through which the bolt passes; and

a support portion for fixing the bolt inserted through the through hole,

in this fastening configuration, the first and second fastening means,

the nominal diameter of the bolt is d, the depth of the through hole is L, and the loosening starting angle of the bolt is 0.02 xL/d⁴In the above, the nominal diameter of the bolt and the depth of the through hole are in mm, and the loosening start angle of the bolt is in °.

8. A fastening structure is provided with:

a bolt;

a contact surface portion having a Vickers hardness of 300Hv or more and receiving a head portion of the bolt; and

a support portion for fixing the bolt,

in this fastening configuration, the first and second fastening means,

the bolt has a nominal diameter d, a depth L of the through hole between the contact surface portion and the support portion, and a loosening start angle of 0.02 xL/d⁴In the above, the nominal diameter of the bolt and the depth of the through hole are in mm, and the loosening start angle of the bolt is in °.

Technical Field

The present invention relates to a fastening structure using a bolt and an industrial machine including the fastening structure.

Background

Fastening using a bolt is widely performed in various fields. As an example, a reduction gear of an eccentric oscillation type or the like (JP2017-65301A) is fastened with a member that outputs rotation from the reduction gear using a bolt. The output of the reduction gear continues to increase due to the requirement for high-speed driving, and along with this, the number of bolts used for fastening also increases.

However, it is also desired to miniaturize the reduction gear, and there is a limit to the number of bolts that can be provided. On the other hand, if the fastening force of each bolt is increased, the reduction gear is deformed. Such deformation may cause loosening and play in the fastening structure itself, and eventually may cause breakage of the fastening structure.

Disclosure of Invention

The present invention has been made in view of the above points, and an object thereof is to provide a fastening structure capable of stably maintaining a fastened state, and an industrial machine including the fastening structure.

The 1 st fastening structure of the present invention includes:

a bolt;

a through hole through which the bolt passes;

a contact surface portion having a Vickers hardness of 300Hv or more and adapted to receive the head of the bolt; and

a support portion for fixing the bolt inserted through the through hole,

the nominal diameter of the bolt is d [ mm ], the depth of the through hole is L [ mm ], and the loosening starting angle of the bolt is 0.02 xL/d⁴And (l) above.

The 2 nd fastening structure of the present invention includes:

a bolt;

a contact surface portion having a Vickers hardness of 300Hv or more and receiving a head portion of the bolt;

a through hole through which the bolt passes; and

a support portion for fixing the bolt inserted through the through hole,

in this 2 nd fastening configuration,

the nominal diameter of the bolt is d [ mm ], the depth of the through hole is L [ mm ], and the loosening starting angle of the bolt is 0.02 xL/d⁴And (l) above.

The 3 rd fastening structure of the present invention includes:

a bolt;

a contact surface portion having a Vickers hardness of 300Hv or more and receiving a head portion of the bolt; and

a support portion for fixing the bolt,

in this 3 rd fastening configuration,

the bolt has a nominal diameter of d [ mm ], a depth of a through hole between the contact surface portion and the support portion of L [ mm ], and a loosening start angle of 0.02 xL/d⁴And (l) above.

The 4 th fastening structure of the present invention includes:

a bolt;

a 1 st member having: a through hole through which the bolt passes; and a contact surface portion having a Vickers hardness of 300Hv or more and receiving a head portion of the bolt; and

a 2 nd member for fixing the bolt inserted through the through hole,

the nominal diameter of the bolt is d [ mm ], the depth of the through hole is L [ mm ], and the loosening starting angle of the bolt is 0.02 xL/d⁴And (l) above.

In the 1 st to 4 th fastening structures of the present invention, the bolt may have a nominal diameter of d [ mm ], a depth of the through hole of L [ mm ], and the loosening start angle of the bolt may be 0.06 × L/d⁴[ (DEG) ] below.

In the 1 st to 4 th fastening structures of the present invention, the bolt may have a nominal diameter of d [ mm ], a depth of the through hole of L [ mm ], and the loosening start angle of the bolt may be 0.03 × L/d⁴And (l) above.

In the 1 st to 3 rd fastening structures of the present invention, one of the contact surface portion and the support portion may be a speed reducer. In the 4 th fastening structure of the present invention, one of the 1 st member and the 2 nd member may be a reduction gear.

In the 1 st to 3 rd fastening structures of the present invention, it is also possible,

one of the contact surface portion and the support portion is a 1 st portion of a carrier of a speed reducer,

the other of the contact surface portion and the support portion is a 2 nd portion of a carrier of the speed reducer.

In the 4 th fastening structure of the present invention, the fastener may be,

one of the 1 st and 2 nd members is a 1 st portion of a carrier of a speed reducer,

the other of the 1 st member and the 2 nd member is a 2 nd portion of a carrier of a speed reducer.

The industrial machine of the present invention includes any one of the fastening structures of the present invention described above.

According to the present invention, the fastened state can be stably maintained.

Drawings

Fig. 1 is a diagram for explaining an embodiment, and is a vertical cross-sectional view showing a reduction gear as an example of an application target of a fastening structure.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a perspective view showing an industrial machine including a fastening structure.

Fig. 4 is a sectional view showing a fastening structure.

Fig. 5 is a plan view showing a reduction gear included in the fastening structure of fig. 4.

Fig. 6 is a diagram for explaining a loosening start angle, and is a graph showing a relationship between a torque and a rotation angle of a bolt when loosening the bolt.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 to 6 are views for explaining an embodiment of a fastening structure. Hereinafter, an example in which the fastening structure of the present embodiment is applied to a reduction gear, particularly, an eccentric oscillating type reduction gear will be described as an example. However, the fastening structure of the present embodiment is not limited to the examples described below, and can be applied to various fastening products fastened by using bolts.

First, the overall structure of the eccentric rocking type reduction gear 10 will be described with reference to fig. 1 and 2. The speed reducer 10 includes: the housing 20, the carrier 30, the crankshaft 40, and the two external gears 50a, 50 b. The housing 20 has internal teeth 25. The crankshaft 40 is supported by the carrier 30 and drives the two external gears 50a and 50 b. In the reduction gear 10, the carrier 30 rotates relative to the case 20 about the rotation axis line RA by meshing the external teeth 55 of the external gears 50a, 50b with the internal teeth 25. Hereinafter, a direction parallel to the rotation axis RA is referred to as an axial direction DA, and a direction perpendicular to the rotation axis RA is referred to as a radial direction DR. The axial direction DA and the radial direction DR are orthogonal to the circumferential direction DC centered on the rotation axis RA.

The housing 20 has: a substantially cylindrical case main body 21; and an internal tooth pin 24 held to the inner surface of the housing main body 21. The housing main body 21 is formed with pin grooves arranged along the circumferential direction DC, extending in the axial direction DA, and receives and holds the internal gear pins 24 having a cylindrical shape. The internal tooth pins 24 extend in the axial direction DA, forming internal teeth 25.

The carrier 30 is held by the housing 20 so as to be rotatable about the rotation axis line RA via a pair of bearings 12. The carrier 30 has a carrier base portion (also referred to as "part 1") 31 and a plate portion (also referred to as "part 2") 32 that are fixed to each other by bolts (2 nd bolts) B2. The central axis of the bolt B2 is parallel to the axial direction DA. The carrier base part 31 includes a disk-shaped base plate part 31a and a plurality of column parts 31b projecting from the base plate part 31 a. In the illustrated example, the base plate portion 31a and the plurality of pillar portions 31b are integrally formed. As shown in fig. 2, the plurality of pillar portions 31b are provided at equal intervals in the circumferential direction DC about the rotation axis RA. In the illustrated example, three column portions 31b are provided. A screw hole (2 nd screw hole) SH2 that engages with the bolt B2 is formed in the distal end surface of the column portion 31B. Further, the plate portion 32 is formed with a through hole (2 nd through hole) TH2 that penetrates so as not to engage with the bolt B2. A gap is left between the bolt B2 and the through hole TH 2.

The carrier base portion 31 and the plate portion 32 of the carrier 30 are respectively formed with a central hole 34 located on the rotation axis RA. The carrier 30 is formed with a through hole 35 that penetrates the carrier base part 31 and the plate part 32. The plurality of through holes 35 are provided in the carrier base portion 31 and the plate portion 32 at equal intervals in a circumferential direction DC about the rotation axis RA. In the illustrated example, three through holes 35 are provided in the carrier base part 31 and the plate part 32.

The bearings 13a and 13b are provided in the through hole 35 formed in the carrier base part 31 and the plate part 32. The crankshaft 40 is held rotatably with respect to the carrier 30 by a pair of bearings 13a and 13b provided in the axial direction. Furthermore, rotational axis RAC of crankshaft 40 is parallel to axial direction DA. The crankshaft 40 has an input gear 42 and two eccentric bodies 41a, 41b arranged in the axial direction DA. Each of the eccentric bodies 41a, 41b has a disc-like or cylindrical outer shape. Central axes CAa, Cab of both eccentric bodies 41a, 41b are eccentric symmetrically about rotation axis RAC of crankshaft 40.

The two external gears 50a, 50b are disposed in a space formed between the plate portion 31a and the plate portion 32 of the carrier base portion 31 of the carrier 30. The two external gears 50a, 50b are aligned along the axial direction DA. As shown in fig. 2, a central hole 51 is formed in each of the external gears 50a and 50 b. The external gears 50a and 50b have external teeth 55 aligned along the outer peripheral edge centered on the central hole 51. The number of teeth of the external teeth 55 is smaller (by way of example, only one) than the number of teeth of the internal teeth 25 of the housing 20. Further, the outer diameters of the external gears 50a, 50b are slightly smaller than the inner diameter of the housing 20.

Further, the external gears 50a and 50b are formed with eccentric body through holes 52a and 52b provided at equal intervals in the circumferential direction around the central hole 51. Bearings 13c and 13d are disposed in the eccentric body through holes 52a and 52b, respectively. The eccentric bodies 41a, 41b of the crankshaft 40 are held by the bearings 13c, 13 d.

Further, the external gears 50a and 50b are formed with column portion through holes 53a and 53b provided at equal intervals in the circumferential direction DC around the central hole 51. The post portion through holes 53a and 53b and the eccentric body through holes 52a and 52b are alternately arranged in the circumferential direction around the center hole 51 for each of the external gears 50a and 50 b. Each column portion 31b of the carrier base portion 31 passes through the corresponding column portion through hole 53a, 53b of the external gear 50a, 50 b.

In the reduction gear 10 having the above-described configuration, torque from the driving device 60 such as a motor is transmitted to the input gear 42. In the illustrated example, the input shaft 61 of the drive device 60 is inserted into the central hole 34 of the carrier 30 and the central holes 51 of the external gears 50a and 50b to mesh with the input gear 42. The input shaft 61 rotates about the rotation axis RA. When rotation is transmitted from drive device 60 to input gear 42, crankshaft 40 rotates about rotation axis RAC. At this time, the 1 st eccentric body 41a and the 2 nd eccentric body 41b eccentrically rotate. Further, the respective external gears 50a and 50b oscillate according to the eccentric rotation of the 1 st eccentric body 41a and the 2 nd eccentric body 41 b. More strictly speaking, the external gears 50a and 50b perform translational motion on a circular path around the rotation axis RA with respect to the carrier 30. When the external gears 50a and 50b oscillate, the external teeth 55 of the external gears 50a and 50b mesh with the internal teeth 25 of the housing 20. Since the number of teeth of the external teeth 55 is smaller than that of the internal teeth 25, the external gears 50a and 50b rotate in a wobbling manner with respect to the housing 20. That is, the external gears 50a and 50b further rotate about their central axes while revolving around the rotation axis RA. As a result, the carrier 30 supporting the external gears 50a and 50b via the crankshaft 40 also rotates relative to the housing 20 about the central axis line thereof as the rotation axis RA. In this way, the rotation input from the input shaft 61 of the drive device 60 is decelerated and output as relative rotation between the casing 20 and the carrier 30.

The speed reducer 10 described above is incorporated into, for example, an industrial machine IM and used. More specifically, the reducer 10 can be used together with a drive device in a revolving unit such as a revolving body and a wrist joint of a robot, a revolving unit of various machine tools, and the like. As a specific example shown in fig. 3, by fixing the housing 20 to the base 6X of the robot 6 and connecting the carrier 30 to the revolving unit 6Y of the robot 6, the revolving unit 6Y can be rotated with high torque with respect to the base 6X, and the rotation of the revolving unit 6Y can be controlled with high accuracy.

Here, fig. 4 shows a connection portion where reduction gear 10 is connected to base 6X and revolving unit 6Y in industrial machine IM shown in fig. 3. Fig. 4 shows only a portion constituting a coupling portion of speed reducer 10 to base 6X and rotator 6Y, and for example, external gears 50a and 50b and crankshaft 40 are not shown. Fig. 5 is a plan view showing the reduction gear 10 of fig. 4 from a direction along the rotation axis RA. In the example shown in fig. 5, the reduction gear 10 is shown from the carrier base portion 31 side of the carrier 30. For convenience of illustration, understanding, and the like, the casing 20 and the carrier 30 of the reduction gear 10 shown in fig. 4 and 5 have partially different shapes and sizes from those of the example shown in fig. 1 and 2 referred to for the purpose of explaining the overall structure and operation of the reduction gear 10, but have the same operation and function.

First, a connection portion between the reduction gear 10 and the base 6X will be described. As shown in fig. 4, the housing body 21 of the housing 20 has a flange portion 22 protruding outward on the side away from the rotation axis RA in the radial direction DR. As shown in fig. 5, the flange portion 22 is formed in a ring shape. The flange portion 22 is formed with a plurality of through holes (1 st through hole) TH 1. The plurality of through holes TH1 are arranged at equal intervals in the circumferential direction DC. On the other hand, as shown in fig. 4, a screw hole (1 st screw hole) SH1 is formed in the base 6X of the robot 6 at a position facing each through hole TH 1. The bolt (1 st bolt) B1 passes through the corresponding through hole TH1 of the speed reducer 10 without engaging with it and engages with the corresponding screw hole SH1 of the base 6X. In this manner, the reduction gear 10 and the base 6X are coupled using the plurality of bolts B1. The central axis of the bolt B1 is parallel to the axial direction DA. Further, a gap is left between the bolt B1 and the through hole TH 1.

Next, a connection portion between carrier 30 and rotator 6Y will be described. As shown in fig. 5, a plurality of screw holes (3 rd screw holes) SH3 are formed in a surface of carrier 30 facing rotor 6Y. In the example shown in fig. 5, six screw holes SH3 are formed in each of three regions between the through holes 35 for two adjacent crankshafts 40 in the circumferential direction DC. On the other hand, as shown in fig. 4, through-holes (3 rd through-holes) TH3 are formed in the rotator 6Y of the robot 6 at positions facing the respective screw holes SH 1. Then, the bolt (the 3 rd bolt) B3 passes through the corresponding through hole TH3 of the rotator 6Y and engages with the corresponding screw hole SH3 of the speed reducer 10. In this manner, the reduction gear 10 and the rotator 6Y are coupled using the plurality of bolts B3. The central axis of the bolt B3 is parallel to the axial direction DA. Further, a gap is left between the bolt B3 and the through hole TH 3.

However, as also mentioned in the background section, the reduction gear 10 is required to have a high output, for example, for high-speed driving. When the output from reduction gear 10 is large, the coupling between reduction gear 10 and base 6X and the coupling between reduction gear 10 and revolving unit 6Y need to be stronger. On the other hand, reduction in size is also desired for the reduction gear 10, and as shown in fig. 4 and 5, it may be difficult to increase the number of bolts from the viewpoint of the arrangement space. Further, when the fastening force of each bolt is increased, the contact surface portion forming the contact surface of the bolt is deformed such as sinking. If deformation such as sinking occurs, the fastening force of the bolt is easily loosened.

On the other hand, in the present embodiment, a study is made to stably maintain the fastened state of the fastening structure FS using bolts. As a specific configuration, there is a fastening structure FS having: a bolt; a 1 st member M1 having a through hole through which a bolt passes; and a 2 nd member M2 having a screw hole for engaging with a bolt inserted through the through hole, wherein in the fastening structure FS, first, the Vickers hardness of the 1 st member M1 at the contact surface portion of the head HP of the receiving bolt is 300Hv or more. Further, the loosening start angle of the bolt was set to 0.02 XL/d⁴And (l) above. Here, "L" used for determining the loosening start angle is the depth [ mm ] of the through hole, and "d" is the nominal diameter of the bolt[ mm ]. In addition, the 2 nd member M2 constitutes a support portion for fixing the bolt.

In the example shown in fig. 4 and 5, the 1 st fastening structure FS is configured such that the reducer 10, particularly the flange portion 22 of the housing 20, is the 1 st member M1, and the base 6X of the robot 6 is the 2 nd member M2. In the 1 st fastening structure FS, a contact surface portion SS1 pressed by the head portion HP of the bolt B1 is formed in a region of the surface of the flange portion 22 of the housing main body 21 around each through hole TH 1. The Vickers hardness of the contact surface portion SS1 is 300Hv or more. Further, the loosening start angle of the bolt B1 was 0.02 XL/d⁴And (l) above. In the 1 st fastening structure FS, the base 6X constitutes a support portion SP 1.

In the example shown in fig. 4 and 5, the 2 nd fastening structure FS is configured such that the plate portion (the 2 nd portion) 32 of the carrier 30 is the 1 st element M1, and the carrier base portion (the 1 st portion) 31 of the carrier 30, in particular, the pillar portion 31b of the carrier base portion 31 is the 2 nd element M2. In the 2 nd fastening structure FS, the bottom surface of the recess RP formed to face the through holes TH2 on the surface of the plate portion 32 forms a contact surface portion SS2 pressed by the head portion of the bolt B2. This recess RP forms a receiving portion for receiving the head of the bolt B2. The Vickers hardness of the contact surface portion SS2 is 300Hv or more. Further, the loosening start angle of bolt B2 was 0.02 XL/d⁴And (l) above. In the 2 nd fastening structure FS, the carrier base part 31 constitutes a support part SP 2.

In the example shown in fig. 4 and 5, the 3 rd fastening structure FS is configured such that the revolving structure 6Y of the robot 6 is the 1 st member M1, and the reduction gear 10, in particular, the carrier 30 of the reduction gear 10 (more specifically, the base plate portion 31a of the carrier base portion 31) is the 2 nd member M2. In the 3 rd fastening structure FS, a contact surface portion SS3 pressed by the head portion of the bolt B2 is formed in a region of the surface (inner surface) of the rotator 6Y around each through hole TH 3. The Vickers hardness of the contact surface portion SS3 is 300Hv or more. Further, the loosening start angle of bolt B3 was 0.02 XL/d⁴And (l) above. In addition, in the 3 rd fastening structure FS, the carrier base portion 31 structureThe support portion SP3 is formed.

Here, the Vickers hardness is a value measured in accordance with JIS Z2244, and is measured by using a hardness tester 810-352 manufactured by Mitutoyo.

On the other hand, the loosening start angle is an angle [ (° ] obtained by rotating bolts B1 to B3 until the torque for loosening bolts B1 to B3 is rapidly reduced. When loosening a bolt, the relationship between the torque applied to the bolt and the rotation angle of the bolt is generally as shown in fig. 6. That is, while the bolt is loosened by rotating the bolt by a certain rotation angle, the torque is slightly reduced although it is slight. The decrease at this time is substantially continuous. On the other hand, when the bolt is rotated by a certain rotation angle, the fastening force is rapidly reduced, and the torque for rotating the bolt is rapidly reduced. The angle [ (° ] of the bolt rotated until the torque changes rapidly in this manner is referred to as the loosening start angle. By making a graph by studying the relationship between the torque applied to loosen the bolt and the rotation angle of the bolt, that is, by making the graph of fig. 6, the loosening start angle of the bolt can be specified [ (° ]).

In the present embodiment, the minimum value of the loosening start angle ([ - ] C ] is determined in consideration of the depth L [ mm ] of the through hole and the nominal diameter d [ mm ] of the bolt, and also in consideration of the friction coefficient [ μ w ] between the bolt and the contact surface and the friction coefficient [ μ s ] between the threaded portion of the bolt and the support portion. The portions of bolts B1 through B3 located in threaded holes SH1, SH2, and SH3 can engage with threaded holes SH1, SH2, and SH3 over the entire length of the portions. On the other hand, the portions of bolts B1 through B3 located in through holes TH1, TH2, and TH3 are twisted without being restricted by through holes TH1, TH2, and TH3 by the torque for loosening bolts B1 through B3. Therefore, since the influence of the torsion angle at the portion of the bolt located within the through hole is omitted, the minimum value of the loosening start angle is determined in consideration of the depth L [ mm ] of the through hole and the nominal diameter d [ mm ] of the bolt.

By setting the vickers hardness at the contact surface portions SS1, SS2, and SS3 to 300Hv or more, more preferably 400Hv or more, and still more preferably 450Hv or more, it is possible to effectively suppress deformation such as sinking at the contact surface portions SS1, SS2, and SS3, and to fasten the bolts B1, B2, and B3 to the screw holes SH1, SH2, and SH3 with high fastening force. Furthermore, the vickers hardness at the contact surface portions SS1, SS2, and SS3 can be adjusted by the presence or absence of quenching and the change in quenching conditions.

In addition, in the component (member) having the contact surface portions SS1, SS2, and SS3, it is preferable that the entire component be hardened by setting the vickers hardness to 300Hv or more only on the surface of the portion including the contact surface portions SS1, SS2, and SS 3. That is, it is preferable to apply hardening only to the contact surface portions SS1, SS2, and SS3 without applying full-scale hardening while paying attention to workability and working accuracy of the parts. Specifically, the hardness of the contact surface portions SS1, SS2, and SS3 can be increased by performing laser hardening on the contact surface portions SS1, SS2, and SS 3. Compared with the integral quenching of the parts, the deformation is less, and the high precision of the shapes of the parts can be maintained. The partial hardening treatment is not limited to laser hardening, and may be a treatment of applying a high surface pressure to the surface by induction hardening.

In addition, the following were confirmed: by setting the loosening start angle of the bolt to 0.02 xL/d⁴[ (DEG) ] or more, preferably 0.03X L/d⁴[ (DEG) ] or more, and more preferably 0.04X L/d⁴[ (DEG) ] or more, the fastened state of the 1 st member M1 and the 2 nd member M2 using the bolt can be stably maintained without increasing the fastening force of the bolt more than necessary. Further, the loosening start angle of the bolt can be adjusted not only by adjusting the fastening force of the bolt but also by adjusting the surface hardness of the 1 st member M1, the engagement length of the bolt with the threaded hole, the frictional force between the bolt and the 1 st member M1, the frictional force between the 1 st member M1 and the 2 nd member M2, and the like.

When the fastening structure FS is applied to the speed reducer 10, the vickers hardness of the contact surface portions SS1, SS2, and SS3 can be set to 500Hv or less. In the use of the speed reducer 10, particularly in the use of the speed reducer 10 for the industrial machine IM, the vickers hardness exceeding 500Hv is rarely required. In addition, in the fastening structure FS decreasesIn the application of the governor 10, it is preferable that the loosening start angle of the bolt is 0.06 XL/d⁴And (d) below so as not to make the operation, such as maintenance, difficult.

As described above, in the present embodiment, the fastening structure FS includes: bolts B1, B2, B3; through holes TH1, TH2, and TH3 through which bolts B1, B2, and B3 penetrate; contact surface portions SS1, SS2, and SS3 having a vickers hardness of 300Hv or more and adapted to receive bolts B1, B2, and B3; and support portions SP1, SP2, and SP3 for fixing bolts B1, B2, and B3 inserted through holes TH1, TH2, and TH 3. More specifically, the fastening structure FS has: bolts B1, B2, B3; 1 st member M1, 10, 20, 32, 6Y having through holes TH1, TH2, TH3 penetrated by bolts B1, B2, B3, and having vickers hardness of 300Hv or more at contact surface portions SS1, SS2, SS3 for receiving bolts B1, B2, B3; and 2 nd members M2, 6X, 31a, 10, 30 having screw holes SH1, SH2, SH3 engaged with bolts B1, B2, B3 penetrating through the through holes TH1, TH2, TH 3. The nominal diameters of bolts B1, B2 and B3 are d [ mm ], the depths of through holes TH1, TH2 and TH3 are L [ mm ], and the loosening start angles of bolts B1, B2 and B3 are 0.02 XL/d⁴And (l) above. According to such a fastening structure FS, the hardness of the contact surface portions SS1, SS2, and SS3 is set to a sufficiently high value, and thus, deformation (e.g., sinking) of the contact surface portions SS1, SS2, and SS3 can be effectively avoided, and a sufficiently large loosening start angle can be ensured. By increasing the loosening start angle, the state in which bolts B1, B2, and B3 are engaged with screw holes SH1, SH2, and SH3 of members 2M 2, 6X, 31a, 10, and 30 can be stably maintained.

In the specific example of the above-described embodiment, one of the 1 st member M1 and the 2 nd member M2 is used as the speed reducer 10, and particularly, the housing 20 or the carrier 30 of the speed reducer 10. Therefore, the speed reducer 10 and the 1 st member M1 or the 2 nd member M2 can be maintained in a stably fastened state using bolts. This increases the output of the transmission 10, and enables high torque to be output to the 1 st member M1 or the 2 nd member M2.

In the specific example of the above-described embodiment, one of the 1 st member M1 and the 2 nd member M2 is defined as the 1 st portion (carrier base portion) 31 of the carrier 30 of the transmission 10, and the other of the 1 st member M1 and the 2 nd member M2 is defined as the 2 nd portion (plate portion) 32 of the carrier 30 of the transmission 10. The 1 st and 2 nd parts 31 and 32 of the carrier 30 can be maintained in a stably fastened state using bolts. Therefore, the output of the small reduction gear 10 can be increased to output a high torque.

The embodiments have been described with reference to specific examples, which are not intended to limit the embodiments. The above-described embodiment can be implemented in various other specific examples, and various omissions, substitutions, changes, and additions can be made without departing from the spirit thereof.

For example, in the above-described specific example, the 2 nd member M2 having the screw hole is shown as a component of the speed reducer 10 or the robot 6, but the present invention is not limited to this example, and the 2 nd member M2 may be a nut. The screw hole to which the bolt is engaged may be a bottomed hole as in the illustrated example, or may be a through hole.

In addition, although an example in which the fastening structure FS is applied to an eccentric oscillating type reduction gear is shown, the present invention is not limited thereto. The fastening structure FS may be applied to a swirler type speed reducer or a planetary gear type speed reducer. The application target of the fastening structure FS is not limited to the reduction gear, and can be applied to various gear transmission devices and the like.