JP5508320B2 - Gear device - Google Patents

Description

  The present invention relates to a gear device in which a mating member can be fastened to a base of a carrier with a bolt or the like.

  The gear device is often fastened by using a male screw member such as a bolt between a pair of members that are relatively rotationally driven. The gear device disclosed in Patent Document 1 is fixed to a movable arm and a fixed base of an industrial robot by bolts.

  As shown in FIGS. 7A, 7 </ b> B, and 8, the gear device 101 described in Patent Document 1 includes an outer cylinder 102 in which a plurality of inner teeth 103 are provided on the inner surface, and the outer cylinder 102. A crankshaft 108 that is rotatably provided and has an eccentric portion 108a, a swing gear 110 that is attached to the eccentric portion 108a, swings and rotates while meshing with the internal teeth 103 in conjunction with the eccentric rotation of the eccentric portion 108a, and a crank And a carrier 104 having a base 113 to which a shaft 108 is rotatably attached. The carrier 104 is accommodated inside the outer cylinder 102 so as to be rotatable relative to the outer cylinder 102.

  In this gear device 101, the base 113 of the carrier 104 is fastened to the robot arm 151 with bolts 111 and 112 made of coarse screws, and the outer cylinder 102 is fastened to the robot base 152 with bolts 133.

  A plurality of bolt holes 131 and 132 are formed in the attachment surface 113 c of the base portion 113 of the carrier 104 to the arm 151. The bolts 111 and 112 penetrate the arm 151 and are screwed into the bolt holes 131 and 132 of the mounting surface 113 c of the base 113, whereby the carrier 104 is fastened to the arm 151.

  The mounting surface 113c is formed with an opening 120 in which the spur gear 107 for driving the crankshaft 108 and the drive gear D of the motor M are accommodated. For this reason, the bolt holes 131 and 132 are disposed at a place avoiding the opening 120.

JP 2006-31957 A

It is desirable to increase the axial force of the bolts 111 and 112 so that the base member 113 of the carrier 104 and the mating member such as the arm 151 are not displaced relatively to each other. However, in the gear device described in Patent Document 1 as described above, an opening 120 in which the spur gear 107 and the drive gear D are accommodated is formed on the mounting surface 113c of the base portion 113 of the carrier 104 to the arm 151. since, in such a mounting surface 113c, a region for forming the bolt holes 131 and 132 is limited, especially the side closer to the rotation center O ₃ of the carrier 4, i.e. the regions that form as the bolt holes 132 made on the inner diameter side is restricted. Therefore, since an area for forming a large number of bolt holes 132 cannot be obtained on the inner diameter side of the mounting surface 113c of the base portion 113, the outer diameter of the screw is large in order to secure an axial force as the bolt 112 on the inner diameter side. I have to adopt bolts.

  Therefore, since the bolt 112 having a large male screw diameter is disposed on the mounting surface 113c of the base 113, it is difficult to reduce the size of the gear device.

  Therefore, the present invention has been made in view of such a point, and ensures the axial force of the male screw member even when the region where the screw hole is formed on the mounting surface of the carrier base to the mating member is limited. It is an object of the present invention to provide a gear device that can be used.

  The gear device of the present invention includes an outer cylinder having a plurality of inner teeth provided on an inner surface, a crank member that is rotatably provided in the outer cylinder and having an eccentric part, and is attached to the eccentric part. An external gear that oscillates and rotates while meshing with the internal teeth in conjunction with the eccentric rotation of the shaft, and a base portion that includes a space portion that rotatably stores the crank member, and is relative to the outer cylinder. And a carrier housed in the outer cylinder so as to be rotatable, and a coarse screw for fastening the base of the carrier to the mating member is fastened to the mounting surface of the base of the carrier to the mating member A first female screw hole having a possible shape, and a fine line arranged on the inner diameter side of the first female screw hole with respect to the center of rotation of the carrier with respect to the outer cylinder, and fastening the base of the carrier to the mating member Screw can be fastened It is characterized in that a second internally threaded hole having Jo is formed.

  According to such a configuration, the first female screw hole to which the coarse screw can be fastened on the outer diameter side is formed on the attachment surface of the carrier base to the mating member as viewed from the center of rotation of the carrier with respect to the outer cylinder. A second female screw hole to which a fine screw can be fastened is formed on the inner diameter side. Therefore, when a coarse screw is fastened to the first female screw hole and a fine screw is fastened to the second female screw hole, the fine screw on the inner diameter side has a larger axial force than the coarse screw. It is possible to fasten with the mating member. Therefore, even when the region for forming the female screw hole is limited on the inner diameter side of the mounting surface, the axial force can be secured by the fine screw on the inner diameter side. Accordingly, it is not necessary to enlarge the second female screw hole on the inner diameter side, and the gear device can be easily downsized.

  Further, the gear device is applied to a drive unit that rotationally drives the revolving body of the robot relative to the base, and includes a first male screw member that is a coarse screw and a second male screw that is a fine screw. And the counterpart member is one member of the revolving body or base of the robot, and the first male screw member penetrates the revolving body or base and the first member is the first member. When the second male screw member is screwed into the second female screw hole through the swivel body or the base, the swivel body or the base is attached to the base portion. It may be concluded.

  According to this configuration, the first male screw member made of coarse screws passes through the revolving body or base of the robot and is screwed into the first female screw hole, and the second male screw member made of fine screws is When the swivel body or base is fastened to the base of the carrier by swiveling or passing through the base body and screwed into the second female screw hole, the area where the female thread hole is formed on the mounting surface is limited However, it is possible to fasten the swivel body or the base to the base portion with a larger axial force than the coarse screw by the fine screw on the inner diameter side. Therefore, the possibility that the revolving body or the base is displaced with respect to the base is reduced. Further, when a moment due to an external force is applied to the swivel body or the base, the moment is received by the first male screw member made of coarse threads positioned on the outer diameter side, so that the first male screw member on the outer diameter side Although only the axial force increases, the axial force of the second male screw member made of the fine thread on the inner diameter side hardly increases. Therefore, even if the second male screw member is tightened so that the axial force of the second male screw member on the inner diameter side is increased to near the limit of the tensile strength, the second male screw member breaks when a moment due to an external force is applied. Is less likely to do.

  Further, the apparatus further includes a first male screw member made of coarse screws and a second male screw member made of fine screws, and the carrier is disposed on an end face of the base portion facing the rotation axis direction of the carrier. The mating member is the end plate portion, the first male screw member passes through the end plate portion and is screwed into the first female screw hole, and The end plate portion may be fastened to the base portion by the second male screw member passing through the end plate portion and screwed into the second female screw hole.

  According to this configuration, the first male screw member made of coarse screws passes through the end plate portion of the carrier and is screwed into the first female screw hole, and the second male screw member made of fine screws is the end. Since the end plate portion of the carrier is fastened to the base portion by passing through the plate portion and screwed into the second female screw hole, the inner diameter is limited even when the region where the female screw hole is formed on the mounting surface is limited. The end plate portion can be fastened to the base portion with a larger axial force than the coarse screw by the fine screw on the side. Therefore, the possibility that the end plate portion is displaced from the base portion is reduced. Further, when a moment due to an external force acts on the end plate portion or the base portion, the moment is received by the first male screw member made of a coarse screw positioned on the outer diameter side, so the first male screw member on the outer diameter side However, the axial force of the second external thread member made of the fine thread on the inner diameter side hardly increases. Therefore, even if the second male screw member is tightened so that the axial force of the second male screw member on the inner diameter side is increased to near the limit of the tensile strength, the second male screw member breaks when a moment due to an external force is applied. Is less likely to do.

  The second male screw member preferably has the same nominal diameter as the first male screw member.

  According to such a configuration, the second male screw member made of fine screws has the same nominal diameter as the first male screw member made of coarse screws, and therefore these male screw members are tightened with a common tightening tool. It is possible. Moreover, when the coarse screw and the fine screw are tightened with the same tightening torque, the axial force of the fine screw on the inner diameter side can be made larger than the axial force of the coarse screw on the outer diameter side. Therefore, in the operation of fastening the first and second male screw members, there is no need to change the tool or the tightening torque, so workability is good.

  As described above, according to the present invention, the axial force of the male screw member can be ensured even when the region where the screw hole is formed is limited on the mounting surface of the carrier at the base member to the mating member.

It is a figure which shows the state by which the turning body of the robot was fastened by the gear apparatus which concerns on embodiment of this invention, (a) is sectional drawing of a gear apparatus, (b) is a rotating shaft direction in the base of the carrier of (a) It is the top view seen from. It is a left view of the gear apparatus of Fig.1 (a). It is sectional drawing which shows the gear apparatus which concerns on other embodiment of this invention. It is a right view of the gear apparatus of FIG. It is a graph which shows the relationship between the moment load and axial force in the gear apparatus of this invention. It is a graph which shows the relationship between the moment load and axial force in the gear apparatus considered conventionally. It is a figure which shows the state by which the arm of the robot was fastened by the gear apparatus of the conventional gear apparatus, (a) is sectional drawing of a gear apparatus, (b) looked at the base of the carrier of (a) from the rotating shaft direction. It is a top view. It is a left view of the gear apparatus of Fig.7 (a).

  Hereinafter, the connection structure of a gear device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
The gear device according to the first embodiment is a gear device that is applied as a speed reducer to, for example, a turning portion such as a turning barrel or arm joint of a robot or a turning portion of various machine tools. In the following description of the present embodiment, an example in which a gear device is applied to a revolving body such as a robot arm will be described.

  As shown in FIG. 1A, the gear device 1 according to the first embodiment transmits a rotational force between a revolving body 51 and a base 52 at a predetermined reduction ratio. The swivel body 51 is included in the concept of the mating member of the present invention. The gear device 1 of the present embodiment includes an outer cylinder 2, an internal tooth pin 3, a carrier 4, a main bearing 6, a crankshaft gear 7, a crankshaft 8, a crank bearing 9, and a swing gear 10. The first bolt 11 and the second bolt 12 are provided.

  The outer cylinder 2 is formed in a substantially cylindrical shape and functions as a case constituting the outer surface of the gear device. The outer cylinder 2 is fastened to the base 52 of the robot with bolts, for example. On the inner surface of the outer cylinder 2, a large number of internal tooth pins 3 are arranged at equal intervals in the circumferential direction. The internal tooth pin 3 functions as an internal tooth with which the oscillating gear 10 made of an external gear meshes. The number of teeth of the oscillating gear 10 is slightly smaller than the number of internal tooth pins 3. In the present embodiment, two (plural) oscillating gears 10 are used.

  The carrier 4 is supported so as to be relatively rotatable with respect to the outer cylinder 2 by a pair of main bearings 6 that are provided apart from each other in the axial direction. The carrier 4 includes a base portion 13 and an end plate portion 14. Between the base portion 13 and the end plate portion 14, a swing gear 10 that is a transmission member that transmits a rotational force between the outer cylinder 2 and the carrier 4 is disposed.

  The base portion 13 includes a substrate portion 13 a disposed in the outer cylinder 2 in the vicinity of the end portion of the outer tube 2, and a shaft portion 13 b extending in the axial direction from the substrate portion 13 a toward the end plate portion 14.

  The end plate portion 14 is disposed on the distal end surface 13 d of the shaft portion 13 b of the base portion 13. The end plate portion 14 is fastened to the shaft portion 13 b by bolts 15. Thereby, the base 13 and the end plate part 14 are integrated.

  As shown in FIGS. 1 (a) and 1 (b), the base 13 has a mounting surface 13c to the revolving body 51 at a portion opposite to the tip surface 13d where the end plate portion 14 is disposed. ing. The mounting surface 13c is formed with an opening 20 in which the three crankshaft gears 7 are accommodated. The opening 20 communicates with a space for accommodating the crankshaft 8 inside the base 13. A plurality of first bolt holes 31 and second bolt holes 32 are formed in a region around the opening 20 on the mounting surface 13c.

The first bolt hole 31 has a female screw shape to which the first bolt 11 formed of a coarse screw that fastens the base portion 13 to the revolving body 51 can be fastened. The first bolt holes 31 are distributed in three places in units of five along the outer peripheral edge of the mounting surface 13c. The first bolt hole 31 of each is from the rotational center O ₁ is located equidistant.

The second bolt hole 32 is on the inner diameter side with respect to the rotation center O _{1 with} respect to the outer cylinder 2 of the carrier 4 than the first bolt hole 31 (that is, the side closer to the rotation center O ₁ than the first bolt hole 31). Is arranged. The second bolt hole 32 has a female screw shape to which the second bolt 12 formed of a fine screw for fastening the base portion 13 to the revolving body 51 can be fastened. Two second bolt holes 32 are arranged at positions on the inner diameter side with respect to the place where the first bolt holes 31 are formed. Each of the second bolt hole 32 is from the rotational center O ₁ is located equidistant.

  The first bolt hole 31 and the second bolt hole 32 have the same inner diameter, and bolts having the same nominal diameter can be screwed in.

  The carrier 4 is fastened to the swing body 51 by the first bolt 11 and the second bolt 12. When the carrier 4 rotates relative to the outer cylinder 2, the swing body 51 rotates with respect to the base 52.

  The 1st volt | bolt 11 consists of the coarse thread which fastens the base 13 of the carrier 4 to the turning body 51, and is the concept contained in the 1st external thread member of this invention.

  The second bolt 12 is a concept included in a second male screw member that is a fine screw that fastens the base portion 13 of the carrier 4 to the revolving body 51.

  In the first embodiment, the second bolt 12 made of fine threads has the same nominal diameter as the first bolt 11 made of coarse threads. That is, the first bolt 11 and the second bolt 12 have the same outer diameter of the male screw portion, and the shape of each bolt head is common, and can be tightened with a common tool.

  In this embodiment, the carrier 4 is fastened to the revolving body 51 so as to turn, and the outer cylinder 2 is fixed to the base 52 so as not to move. However, the outer cylinder 2 is fastened to the revolving body 51 and the carrier 4 is fixed. Of course, the base 13 can be fastened to the base 52 for use.

  A plurality of crankshafts 8 (three in FIG. 1B) are provided, and each crankshaft 8 is arranged around the drive gear D of the motor M at equal intervals in the circumferential direction. A crankshaft gear 7 is attached to the end of each crankshaft 8. Each crankshaft gear 7 meshes with the drive gear D of the motor M. Each crankshaft gear 7 transmits the rotation of the drive gear D to the crankshaft 8 to which the crankshaft gear 7 is attached. Each crankshaft 8 is attached to the carrier 4 via a pair of crank bearings 9 so as to be rotatable around the axis. That is, the crankshaft 8 is rotatably supported by the carrier 4.

  The crankshaft 8 has a plurality (two in FIG. 1A) of eccentric portions 8a. The plurality of eccentric portions 8 a are arranged in the axial direction at a position between the pair of crank bearings 9. Each eccentric portion 8a is formed in a cylindrical shape that is eccentric from the axis of the crankshaft 8 by a predetermined amount of eccentricity. And each eccentric part 8a is formed in the crankshaft 8 so that it may have a phase difference of a predetermined angle mutually.

  The two oscillating gears 10 are attached to the eccentric portions 8a of the crankshaft 8 via roller bearings 18 respectively. The oscillating gear 10 is formed to be slightly smaller than the inner diameter of the outer cylinder 2 and meshes with the internal tooth pin 3 on the inner surface of the outer cylinder 2 in conjunction with the eccentric rotation of the eccentric portion 8a when the crankshaft 8 rotates. Oscillates and rotates.

  The oscillating gear 10 includes a central portion through hole 10b, a plurality of eccentric portion insertion holes 10c, and a plurality of shaft portion insertion holes 10d. The drive shaft DS of the motor M is inserted with play in the central through hole 10b.

  The eccentric part insertion holes 10c are provided at equal intervals in the circumferential direction around the central part through hole 10b in the oscillating gear 10. The eccentric portions 8a of the crankshafts 8 are inserted through the eccentric portion insertion holes 10c with the roller bearings 18 interposed therebetween.

  The shaft portion insertion holes 10d are provided at equal intervals in the circumferential direction around the central portion through hole 10b in the oscillating gear 10. Each shaft portion insertion hole 10d is disposed at a position between the eccentric portion insertion holes 10c in the circumferential direction. Each shaft portion 13b of the carrier 4 is inserted into each shaft portion insertion hole 10d with play.

  Next, the operation of the gear device 1 according to the present embodiment will be described.

  The rotational driving force of the driving gear D generated by the motor M is directly transmitted to each crankshaft gear 7. Thereby, each crankshaft 8 rotates around each axis.

  As each crankshaft 8 rotates, the eccentric portion 8a of the crankshaft 8 rotates eccentrically. As a result, the oscillating gear 10 oscillates and rotates while meshing with the inner tooth pin 3 on the inner surface of the outer cylinder 2 in conjunction with the eccentric rotation of the eccentric portion 8a. The swing rotation of the swing gear 10 is transmitted to the carrier 4 through each crankshaft 8. In this embodiment, since the outer cylinder 2 is fixed to the base 52 and does not move, the carrier 4 and the revolving body 51 are thereby rotated with respect to the outer cylinder 2 and the base 52 at the rotational speed decelerated from the input rotation. Relative rotation.

(Characteristics of the first embodiment)
(1)
In the gear device 1 according to the first embodiment, as shown in FIGS. 1A and 1B and FIG. 2, the outer surface of the carrier 4 is provided on the mounting surface 13 c of the base portion 13 of the carrier 4 to the revolving body 51. the rotation center O ₁ viewed against 2, first bolt holes 31 coarse thread on the outer diameter side that can be fastened is formed, and the second bolt holes 32 fine thread is fastening is formed on the inner diameter side. Therefore, the first bolt 11 made of a coarse screw is fastened to the first bolt hole 31, and the second bolt 12 made of a fine screw having the same outer diameter as the first bolt 11 is fitted to the second bolt hole 32. When tightened with the same tightening torque as that of one bolt 11, the second bolt 12 (fine screw) on the inner diameter side has a larger axial force than the first bolt 11 (coarse screw). The revolving body 51 can be fastened. Therefore, even when the area where the first bolt hole 31 and the second bolt hole 32 are formed on the inner diameter side of the mounting surface 13c is limited, the axial force can be secured by the second bolt 12 on the inner diameter side. . Accordingly, it is not necessary to enlarge the second bolt hole 32 on the inner diameter side, and the gear device can be easily downsized.

(2)
In the gear device 1 according to the first embodiment, when the swivel body 51 is attached to the base portion 13 of the carrier 4, the first bolt 11 formed of a coarse screw is in a state where the swivel body 51 is in contact with the mounting surface 13 c of the base portion 13. The revolving body 51 passes through the revolving body 51 and is screwed into the first bolt hole 31 on the outer diameter side of the base portion 13, and the second bolt 12 made of a fine screw passes through the revolving body 51 and the second bolt hole on the inner diameter side of the base portion 13. 32 is screwed. Thereby, even when the area | region which forms the 1st bolt hole 31 and the 2nd bolt hole 32 in the attachment surface 13c is restrict | limited, the 1st volt | bolt 11 (coarse thread) by the 2nd volt | bolt 12 (fine thread) of an internal diameter side. It is possible to fasten the swivel body 51 to the base 13 with a larger axial force. Therefore, the possibility that the revolving body 51 is displaced from the base portion 13 is reduced.

(3)
In the first embodiment, since the second bolt 12 made of fine screws has the same nominal diameter as the first bolt 11 made of coarse screws, the first bolt 11 and the second bolt 12 are connected to a common tightening screw. It can be tightened with an attached tool (such as a torque wrench). In addition, when the first bolt 11 made of coarse screws and the second bolt 12 made of fine screws are tightened with the same tightening torque, the axial force of the second bolt 12 (fine screw) on the inner diameter side is adjusted to the first bolt on the outer diameter side. It is possible to make it larger than the axial force of one bolt 11 (coarse screw). For this reason, in the operation of fastening the first bolt 11 and the second bolt 12, there is no need to change the tool or the tightening torque, so workability is good.

(4)
When a moment due to an external force is applied to the swing body 51, the moment is received by the first bolt 11 (coarse screw) on the outer diameter side, so only the axial force of the first bolt 11 on the outer diameter side increases. However, the axial force of the second bolt 12 (fine screw) on the inner diameter side hardly increases. Therefore, even if the second bolt 12 is tightened so as to increase the axial force of the second bolt 12 on the inner diameter side to near the limit of the tensile strength (for example, yield point), the second bolt is applied when a moment due to an external force is applied. 12 is less likely to break.

  Here, the relationship between the moment by an external force and the axial force of a bolt is demonstrated.

  In the gear device 1 incorporated in the industrial robot, torque generated by driving the motor M is applied to the fastening portion by the first bolt 11 and the second bolt 12 between the base portion 13 of the carrier 4 and the revolving body 51. In addition to acting, a moment due to an external force or the like transmitted through the revolving body 51 may also act. Conventionally, when a large moment is applied to the fastening portion by an external force, it has been considered that the axial force of the bolt increases for all bolts arranged on the outer diameter side and the inner diameter side.

For example, as shown in FIG. 6, when clamped between the base 13 of the carrier 4 and the turning member 51 from the rotation center O ₁ of the carrier 4 by bolts provided equidistantly, in the initial state after tightening, Even if the axial force of the bolt is _100.0 kN which is lower than the horizontal line L _2max of 120 kN indicating the yield limit of the bolt, if the moment load due to the external force acting on the swing body 51 increases, the axial force of the bolt is also broken. Since it increases like L ₂₀ , when the moment load is double, L ₂₀ may exceed the line L _2max and the bolt may be broken or damaged. For this reason, conventionally, it is arranged on the outer diameter side and the inner diameter side so that the bolt axial force does not reach the yield limit value _L2max of the bolt even if the moment due to the external force acts to increase the bolt axial force. For all bolts, the initial axial force is set low to 80.0 kN in advance, and the bolt does not break or damage beyond the horizontal line L _2max when the moment load is double as shown by the solid line L _21. It was like that.

In consideration of such circumstances, the present inventors have found that each of the bolts for the second bolt 12 of the first bolt 11 and the inner diameter side of the distance from the rotation center O ₁ of the carrier 4 differs from the outer diameter side shaft As a result of intensive studies such as experiments on the relationship between the force and the moment load due to the external force, the experimental results shown in the graph of FIG. 5 were obtained.

As shown in FIG. 5, in the initial state, the first bolt 11 arranged on the outer diameter side and the second bolt 12 on the inner diameter side are respectively connected to the base portion 13 of the carrier 4 so that the axial force of the bolt becomes 80 kN. The revolving body 51 is tightened. When the moment load acting on the swing body 51 (that is, the multiplication factor of the moment due to the external force acting during operation) is increased, the axial force of the first bolt 11 is also corresponding to the solid line L ₁₁ for the first bolt 11 on the outer diameter side. To increase. Therefore, for the first bolt 11 on the outer diameter side, by setting the bolt axial force to advance increased as shown by a broken line L _10, may exceed the horizontal line L _1max showing the yield limit value when the double moment load There is.

On the other hand, the second bolt 12 on the inner diameter side, even if a moment load acting on the turning body 51 is increased, the axial force of the second bolt 12 is substantially maintains the initial value without increase as a chain line L ₁₂ It was found from the experimental results. This is presumably because the first bolt 11 on the outer diameter side receives a moment load, and the second bolt 12 on the inner diameter side is not affected by the moment load.

Therefore, in the present embodiment, the axial force of the second bolt 12 on the inner diameter side is set so as to be _{close to} the horizontal line _L1max indicating the yield limit value as indicated by the solid line L13. Thereby, it is possible to raise the axial force of a volt | bolt between the turning body 51 and the base part 13, and to mutually fasten firmly, thereby, further suppressing the deviation | shift between the turning body 51 and the base part 13 is possible. become.

(Second Embodiment)
In the first embodiment, the example in which the rotating body 51 of the robot is used as the counterpart member fastened to the base portion 13 of the carrier 4 has been described. However, the present invention is not limited to this, and the carrier 4 Any other member that is fastened to the base 13 with a screw member such as a bolt may be fastened. For example, the end plate portion may be firmly fastened to the base portion of the carrier using the first bolt made of coarse threads and the second bolt made of fine screws as described above.

  Specifically, as shown in FIGS. 3 to 4, the gear device 61 of the second embodiment includes an outer cylinder 62, an internal tooth pin 63, a carrier 64, a main bearing 66, and a crankshaft gear 67. , A crankshaft 68, a crank bearing 69, a swing gear 70, a first bolt 71, and a second bolt 72.

  The outer cylinder 62 is formed in a substantially cylindrical shape and functions as a case constituting the outer surface of the gear device. On the inner surface of the outer cylinder 62, a large number of internal tooth pins 63 are arranged at equal intervals in the circumferential direction. The internal tooth pin 63 functions as an internal tooth with which the swing gear 70 made of an external gear meshes.

  The carrier 64 is supported so as to be rotatable relative to the outer cylinder 62 by a pair of main bearings 66 that are separated from each other in the axial direction. The carrier 64 includes a base portion 73 and an end plate portion 74. Between the base portion 73 and the end plate portion 74, a swing gear 70 that is a transmission member that transmits a rotational force between the outer cylinder 62 and the carrier 64 is disposed.

  The base portion 73 has a substrate portion 73a disposed in the outer tube 62 in the vicinity of the end portion of the outer tube 62, and a plurality of shaft portions 73b extending in the axial direction from the substrate portion 73a toward the end plate portion 74. . The base 73 has a space for accommodating the crankshaft 68.

The end plate portion 74 is disposed on the distal end surface 73 d of the shaft portion 73 b that faces the rotation axis O ₂ of the carrier 64 in the base portion 73. The shaft portion 73b is fastened to the end plate portion 74 by the first bolt 71 and the second bolt 72 at the tip end surface 73d. Thereby, the base 73 and the end plate 74 are integrated.

  As shown in FIGS. 3 to 4, the base portion 73 is formed with a plurality of first bolt holes 91 and second bolt holes 92 in a narrow region such as the distal end surface 73 d of the shaft portion 73 b.

The first bolt hole 91 has a female screw shape to which the first bolt 71 formed of a coarse screw that fastens the base 73 to the end plate portion 74 can be fastened. The first bolt holes 91 are distributed and arranged at three locations in units of two along the outer peripheral edge of the distal end surface 73d of the shaft portion 73b. Each of the first bolt hole 91 is from the rotational center O ₂ are arranged equidistantly.

The second bolt hole 92 is disposed on the inner diameter side of the first bolt hole 91 with respect to the rotation center O _{2 with} respect to the outer cylinder 62 of the carrier 64. The second bolt hole 92 has a squeeze shape to which a second bolt 72 made of a fine screw for fastening the base portion 73 to the end plate portion 74 can be fastened. The second bolt hole 92 is formed with the first bolt hole 91. One each is arranged at a position on the inner diameter side with respect to the place where it is located. Each of the second bolt holes 92 from the rotation center O ₂ are arranged equidistantly.

  The first bolt hole 91 and the second bolt hole 92 have the same inner diameter, and bolts having the same nominal diameter can be screwed in.

  The 1st volt | bolt 71 consists of the coarse thread which fastens the base 73 of the carrier 64 to the end plate part 74, and is the concept contained in the 1st external thread member of this invention.

  The second bolt 72 is a concept included in a second male screw member that is a fine screw that fastens the base 73 of the carrier 64 to the end plate portion 74.

  In the first embodiment, the second bolt 72 made of fine threads has the same nominal diameter as the first bolt 71 made of coarse threads. That is, the first bolt 71 and the second bolt 72 have the same outer diameter of the male screw portion, and the shape of each bolt head is common, and can be tightened with a common tool.

  A plurality of crankshafts 68 (three in FIG. 4) are provided, and each crankshaft 68 is arranged around the drive gear D of the motor M at equal intervals in the circumferential direction. A crankshaft gear 67 is attached to the end of each crankshaft 68. Each crankshaft gear 67 meshes with the drive gear D of the motor M, respectively. Each crankshaft gear 67 transmits the rotation of the drive gear D to a crankshaft 68 to which the crankshaft gear 67 is attached. Each crankshaft 68 is attached to the carrier 64 via a pair of crank bearings 69 so as to be rotatable about the axis. That is, the crankshaft 68 is rotatably supported by the carrier 64.

  The crankshaft 68 has a plurality (two in FIG. 3) of eccentric portions 68a. The plurality of eccentric portions 68 a are arranged so as to be aligned in the axial direction at a position between the pair of crank bearings 69. Each eccentric portion 68a is formed in a columnar shape eccentric from the axis of the crankshaft 68 by a predetermined amount of eccentricity. Each eccentric portion 68a is formed on the crankshaft 68 so as to have a phase difference of a predetermined angle.

  The two rocking gears 70 are attached to each eccentric portion 68 a of the crankshaft 68. The oscillating gear 70 is formed to be slightly smaller than the inner diameter of the outer cylinder 62, and meshes with the internal tooth pin 63 on the inner surface of the outer cylinder 62 in conjunction with the eccentric rotation of the eccentric portion 68a when the crankshaft 68 rotates. Oscillates and rotates.

  The oscillating gear 70 includes a central portion through hole 70b, a plurality of eccentric portion insertion holes 70c, and a plurality of shaft portion insertion holes 70d. The drive shaft S that rotationally drives the drive gear D is inserted with play in the central through hole 70b.

  The eccentric portion insertion holes 70 c are provided at equal intervals in the circumferential direction around the central portion through hole 70 b in the swing gear 70. The eccentric portions 68a of the respective crankshafts 68 are inserted into the respective eccentric portion insertion holes 70c with the roller bearings 78 interposed therebetween.

  The shaft portion insertion holes 70d are provided at equal intervals in the circumferential direction around the central portion through hole 70b in the swing gear 70. Each shaft portion insertion hole 70d is disposed at a position between the eccentric portion insertion holes 70c in the circumferential direction. Each shaft portion 73b of the carrier 64 is inserted through each shaft portion insertion hole 70d with play.

(Characteristics of the second embodiment)
(1)
As shown in FIGS. 3 and 4, in the gear device 61 of the second embodiment, the rotation center O of the carrier 64 with respect to the outer cylinder 62 is located in a narrow region of the tip surface 73 d of the shaft portion 73 b in the base 73 of the carrier 64. ₂ , a first bolt hole 91 capable of fastening a coarse screw is formed on the outer diameter side, and a second bolt hole 92 capable of fastening a fine screw is formed on the inner diameter side. Therefore, the first bolt 71 made of coarse thread is fastened to the first bolt hole 91, and the second bolt 72 made of fine thread having the same outer diameter as the first bolt 71 is fastened to the second bolt hole 92. When tightened with the same tightening torque as that of one bolt 71, the second bolt 72 (fine screw) on the inner diameter side has a larger axial force than the first bolt 71 (coarse screw). The end plate portion 74 can be fastened. Therefore, even when the area where the first bolt hole 91 and the second bolt hole 92 are formed on the inner diameter side of the tip end surface 73d of the shaft portion 73b is limited, the axial force is exerted by the second bolt 72 (fine screw) on the inner diameter side. Can be secured. Accordingly, it is not necessary to enlarge the second bolt hole 92 on the inner diameter side, and the gear device 61 can be easily downsized.

(2)
In the gear device 61 of the second embodiment, when attaching the end plate portion 74 to the base portion 73 of the carrier 64, the coarse plate screw is used with the end plate portion 74 in contact with the tip surface 73 d of the shaft portion 73 b of the base portion 73. The first bolt 71 that passes through the end plate portion 74 is screwed into the first bolt hole 91 on the outer diameter side of the base portion 73, and the second bolt 72 that is a fine screw passes through the end plate portion 74 and passes through the base portion 73. Is screwed into the second bolt hole 92 on the inner diameter side. Thereby, even when the area | region which forms the 1st volt | bolt hole 91 and the 2nd volt | bolt hole 92 in the front end surface 73d of the shaft part 73b is restrict | limited, the 1st volt | bolt 71 ( It is possible to fasten the end plate portion 74 to the base portion 73 with an axial force larger than the coarse screw). Therefore, the possibility that the end plate portion 74 is displaced from the base portion 73 is reduced.

(3)
Further, in the second embodiment, as in the first embodiment, the second bolt 72 made of fine threads has the same nominal diameter as the first bolt 71 made of coarse threads, so that these first bolts 71 and The second bolt 72 can be tightened with a common tightening tool (such as a torque wrench). In addition, when the first bolt 71 made of coarse threads and the second bolt 72 made of fine threads are tightened with the same tightening torque, the axial force of the second bolt 72 (fine thread) on the inner diameter side is adjusted to the first bolt on the outer diameter side. It is possible to make it larger than the axial force of one bolt 71 (coarse screw). For this reason, in the work of fastening the first bolt 71 and the second bolt 72, it is not necessary to change the tool or the tightening torque, so that workability is good.

(4)
In the second embodiment, similarly to the first embodiment, when a moment due to an external force acts on the end plate portion 74 or the base portion 73, the moment is converted to the first bolt 71 (coarse screw) on the outer diameter side. Therefore, only the axial force of the first bolt 71 on the outer diameter side increases, but the axial force of the second bolt 72 (fine screw) on the inner diameter side hardly increases. Therefore, even if the second bolt 72 is tightened so as to increase the axial force of the second bolt 72 on the inner diameter side to near the yield point, the second bolt 72 may be broken or damaged when a moment due to an external force is applied. Is low.

  In addition, it should be thought that said 1st and 2nd embodiment disclosed this time is an illustration of this invention in all points, and is not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

  For example, the present invention can be applied not only to a gear device having two oscillating gears 10 as in the above embodiment, but also to a gear device having one oscillating gear or three oscillating gears. Is possible.

  In the embodiment, a plurality of crankshafts 8 are arranged in the circumferential direction. However, only one crankshaft 8 may be provided on the axis of the carrier 4.

1, 61 Gear device 2, 62 Outer cylinder 3, 63 Internal pin 4, 64 Carrier 8, 68 Crankshaft 8a, 68a Eccentric part 10, 70 Oscillating gear 11, 71 First bolt 12, 72 Second bolt 13, 73 Base portion 13b, 73b Shaft portion 13c Mounting surface 13d, 73d End surface 14, 74 End plate portion 31, 91 First screw hole 32, 92 Second screw hole 51 Revolving body 52 Base

Claims (4)

An outer cylinder having a plurality of inner teeth on the inner surface;
A crank member provided rotatably in the outer cylinder and having an eccentric portion;
An external gear that is attached to the eccentric portion and rotates while oscillating while meshing with the internal teeth in conjunction with the eccentric rotation of the eccentric portion;
A base including a space for rotatably storing the crank member, and a carrier housed inside the outer cylinder so as to be rotatable relative to the outer cylinder;
On the mounting surface to the mating member at the base of the carrier,
A first female screw hole having a shape capable of fastening a coarse screw for fastening the base of the carrier to a mating member;
A second female screw that is disposed on the inner diameter side of the first female screw hole with respect to the center of rotation of the carrier with respect to the outer cylinder and has a shape capable of fastening a fine screw that fastens the base of the carrier to the mating member. A gear device characterized in that a hole is formed. The gear device is applied to a drive unit that drives a rotating body of a robot to rotate relative to a base,
A first male screw member comprising coarse screws;
A second male screw member made of fine screws,
The counterpart member is one member of the revolving body or base of the robot,
The first male screw member passes through the swivel body or the base and is screwed into the first female screw hole, and the second male screw member penetrates the swivel body or the base and enters the second female screw. The revolving body or base is fastened to the base by being screwed into a screw hole.
The gear device according to claim 1. A first male screw member comprising coarse screws;
A second male screw member made of fine screws,
The carrier further includes an end plate portion disposed on an end surface of the base portion facing the rotation axis direction of the carrier,
The counterpart member is the end plate portion,
The first male screw member penetrates the end plate portion and is screwed into the first female screw hole, and the second male screw member penetrates the end plate portion and the second female screw hole. The end plate portion is fastened to the base portion by being screwed into the base portion.
The gear device according to claim 1. The second male screw member has the same nominal diameter as the first male screw member.
The gear device according to any one of claims 2 to 3.

Images