JP2014077453A - Eccentric oscillation type gear device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a bolt arranged at a carrier from being loosened.SOLUTION: An eccentric oscillation type gear device 1 comprises an eccentric part 10a, an oscillation gear 14 having a through-hole into which the eccentric part 10a is inserted and an external tooth 14a, an external cylinder 2 and a carrier 4. The carrier 4 has a base part 5 formed with a fastening hole 4f, an end plate part 7 formed with a bolt insertion hole 7c, and a bolt 9 inserted into the bolt insertion hole 7c and fastened to the fastening hole 4f. The bolt 9 is made of iron material. The base part 5 is made of material of which modulus of longitudinal elasticity is smaller than that of iron material such as aluminum alloy etc. The external cylinder 2 and the carrier 4 can be rotated concentrically and relatively to each other under oscillation of a swing gear 14 accompanying with a rotation of the eccentric part 10a.

Description

  The present invention relates to an eccentric oscillating gear device.

  Conventionally, as disclosed in Patent Document 1 below, an eccentric oscillating gear device is known that reduces the rotational speed at a predetermined reduction ratio between two counterpart members. The eccentric oscillating gear device includes an outer cylinder fixed to one counterpart member, and a carrier disposed in the outer cylinder and fixed to the other counterpart member. The carrier has a base plate portion in which a shaft portion is integrally formed and an end plate portion, and an oscillating gear attached to an eccentric portion of the crankshaft between the base plate portion and the end plate portion. In this state, the shaft portion and the end plate portion are fastened to each other by bolts. Then, when the swinging gear swings and rotates while meshing with the inner teeth of the outer cylinder, the carrier and the outer cylinder rotate relatively.

JP 2006-77980 A

  The substrate part, shaft part, and end plate part constituting the carrier are generally made of an iron-based material, and the same applies to bolts. Since there is a processing error in the screw thread formed in the fastening hole of the shaft part and the screw thread of the bolt, not all parts of the screw are engaged with each other when the bolt is fastened. That is, there is a case where only a part of the threads is engaged because the pitch of the threads is slightly varied. In this case, there is a problem that the fastening with the bolt is loosened when the carrier receives an impact.

  The present invention has been made in view of the above prior art, and an object thereof is to prevent the bolts provided on the carrier from being loosened.

  In order to achieve the above object, the present invention provides a gear device that transmits a driving force by converting a rotational speed at a predetermined rotational speed ratio between a first member and a second member. And a swing gear having an insertion hole into which the eccentric portion is inserted and a tooth portion, and the tooth of the swing gear, the tooth of the swing gear being configured to be attachable to one of the first member and the second member. An outer cylinder having internal teeth that mesh with a portion, and a carrier configured to be attachable to the other of the first member and the second member, and the carrier includes a base portion in which a fastening hole is formed; An end plate portion in which an insertion hole is formed; and a bolt that is inserted into the insertion hole and fastened to the fastening hole. The bolt is made of an iron-based material, and the base portion is a vertical member. It is composed of a material whose elastic modulus is lower than the longitudinal elastic modulus of the iron-based material, Yaria and the outer cylinder is eccentrically oscillating gear device to rotate relative to each other by the swing gear with the rotation of the eccentric portion swings while meshing with the internal teeth.

  In this invention, the base part which comprised the carrier and the fastening hole in which a volt | bolt is fastened was comprised with the material whose longitudinal elastic modulus is lower than an iron-type material, and the volt | bolt is comprised with the iron-type material. For this reason, the base is softer than the bolt. Therefore, when the bolt inserted into the insertion hole of the end plate portion is fastened to the base, the thread of the fastening hole is easily elastically deformed. For this reason, even if there is a part where the pitch of the screw thread is slightly different due to a processing error, the strong part of the screw thread of the fastening hole is elastically deformed, so that the entire axial direction of the screw is covered. Thus, the screws can be meshed evenly. Therefore, it is possible to avoid a situation in which the screw thread of the bolt and the screw thread of the fastening hole are engaged with each other, and it is possible to prevent the bolt from loosening when the carrier receives an impact. it can.

  For example, aluminum or an aluminum alloy may be used as a material whose longitudinal elastic modulus is lower than that of the iron-based material. Aluminum alloys are lightweight and have good market availability.

  Here, the outer cylinder may also be made of aluminum or aluminum alloy. In this aspect, the weight of the eccentric oscillating gear device can be further reduced. Further, it can be made less susceptible to the influence of a magnetic field. Moreover, since the heat transfer performance of the outer cylinder can be improved, the heat inside the outer cylinder can be easily released. Therefore, the temperature rise of the oscillating gear can be suppressed, and the thermal expansion of the oscillating gear can be suppressed. As a result, an increase in the surface pressure of the tooth portion of the oscillating gear can be suppressed, and the life of the oscillating gear can be extended.

  As described above, according to the present invention, it is possible to prevent the bolt provided on the carrier from being loosened.

It is sectional drawing which shows the structure of the eccentric rocking | fluctuation type gear apparatus which concerns on embodiment of this invention. It is sectional drawing in the II-II line of FIG.

  Hereinafter, an eccentric oscillating gear device according to an embodiment of the present invention will be described in detail with reference to the drawings. An eccentric oscillating gear device (hereinafter referred to as a gear device) 1 according to this embodiment is applied as a speed reducer to, for example, a revolving part of a revolving trunk or arm joint of a robot, or a revolving part of various machine tools. is there.

  The gear device 1 according to the present embodiment rotates the crankshaft 10 by rotating the input shaft 8, and swings and rotates the swing gears 14 and 16 in conjunction with the eccentric portions 10a and 10b of the crankshaft 10. Thus, an output rotation decelerated from the input rotation is obtained. Thereby, for example, relative rotation can be caused between the base of the robot (one counterpart member) and the swing drum (the other counterpart member). For example, a base is illustrated as a 1st member, for example, a turning body is illustrated as a 2nd member.

  As shown in FIGS. 1 and 2, the gear device 1 includes an outer cylinder 2, a carrier 4, an input shaft 8, a plurality of (for example, three) crankshafts 10, a first swing gear 14, and a second The oscillating gear 16 and a plurality of (for example, three) transmission gears 20 are provided.

  The outer cylinder 2 constitutes the outer surface of the gear device 1 and has a substantially cylindrical shape. A large number of pin grooves 2 b are formed on the inner peripheral surface of the outer cylinder 2. Each pin groove 2b is disposed so as to extend in the axial direction of the outer cylinder 2, and has a semicircular cross-sectional shape in a cross section orthogonal to the axial direction. These pin grooves 2 b are arranged on the inner peripheral surface of the outer cylinder 2 at equal intervals in the circumferential direction.

  The outer cylinder 2 has a large number of internal tooth pins 3. Each internal tooth pin 3 is attached to a pin groove 2b. Specifically, each internal tooth pin 3 is fitted in the corresponding pin groove 2 b and is arranged in a posture extending in the axial direction of the outer cylinder 2. Thereby, the many internal tooth pins 3 are arranged at equal intervals along the circumferential direction of the outer cylinder 2. The first external teeth 14 a of the first oscillating gear 14 and the second external teeth 16 a of the second oscillating gear 16 are engaged with these internal tooth pins 3.

  The outer cylinder 2 is provided with a flange portion, and the flange portion is formed with an insertion hole 2a for inserting a fastener (bolt) for fixing to the base of the robot, for example.

  The carrier 4 is accommodated in the outer cylinder 2 in a state of being arranged coaxially with the outer cylinder 2. The carrier 4 rotates relative to the outer cylinder 2 around the same axis. Specifically, the carrier 4 is arranged on the radially inner side of the outer cylinder 2, and in this state, the carrier 4 can be rotated relative to the outer cylinder 2 by a pair of main bearings 6 provided to be separated from each other in the axial direction. It is supported by.

  The carrier 4 includes a base portion 5 having a substrate portion 4a and a plurality of (for example, three) shaft portions 4c, and an end plate portion 7.

  The substrate portion 4a is disposed in the vicinity of one end portion in the axial direction in the outer cylinder 2. A circular through hole 4d is provided in the central portion in the radial direction of the substrate portion 4a. Around the through hole 4d, a plurality of (for example, three) crankshaft mounting holes 4e (hereinafter simply referred to as mounting holes 4e) are provided at equal intervals in the circumferential direction.

  A fastening hole 4g for fastening a fastener (bolt) (not shown) for fixing the carrier 4 to, for example, a revolving drum of the robot is formed in the substrate portion 4a.

  The end plate portion 7 is provided to be separated from the substrate portion 4a in the axial direction, and is disposed in the vicinity of the other end portion in the axial direction in the outer cylinder 2. A through hole 7 a is provided at the radial center of the end plate portion 7. Around the through hole 7a, a plurality of (for example, three) crankshaft mounting holes 7b (hereinafter simply referred to as mounting holes 7b) are provided at positions corresponding to the plurality of mounting holes 4e of the substrate portion 4a. In the outer cylinder 2, a closed space surrounded by both inner surfaces of the end plate part 7 and the substrate part 4 a facing each other and the inner peripheral surface of the outer cylinder 2 is formed.

  The three shaft portions 4c are provided integrally with the substrate portion 4a, and linearly extend from one main surface (inner surface) of the substrate portion 4a to the end plate portion 7 side. The three shaft portions 4c are arranged at equal intervals in the circumferential direction (see FIG. 2). Each shaft portion 4c is fastened to the end plate portion 7 by bolts 9 (see FIG. 1). That is, a bolt insertion hole 7c is formed in the end plate portion 7, and a fastening hole 4f is formed in the shaft portion 4c (base portion 4) so as to extend in the axial direction from the distal end surface. A bolt 9 is inserted into the bolt insertion hole 7 c of the end plate portion 7 from the side opposite to the base portion 4. The bolt 9 is screwed into the fastening hole 4f of the shaft portion 4c. Thereby, the board | substrate part 4a, the shaft part 4c, and the end plate part 7 are integrated.

  The input shaft 8 functions as an input unit to which a driving force of a driving motor (not shown) is input. The input shaft 8 is inserted into the through hole 7a of the end plate portion 7 and the through hole 4d of the substrate portion 4a. The input shaft 8 is arranged such that its axis coincides with the axes of the outer cylinder 2 and the carrier 4 and rotates around the axis. An input gear 8 a is provided on the outer peripheral surface of the distal end portion of the input shaft 8.

  The three crankshafts 10 are arranged at equal intervals around the input shaft 8 in the outer cylinder 2 (see FIG. 2). Each crankshaft 10 is supported by a pair of crank bearings 12a and 12b so as to be rotatable about the axis with respect to the carrier 4 (see FIG. 1). Specifically, a first crank bearing 12a is attached to a portion on the inside in the axial direction by a predetermined length from one axial end of each crankshaft 10, and the first crank bearing 12a is attached to the mounting hole 4e of the base plate portion 4a. It is attached to. On the other hand, a second crank bearing 12 b is attached to the other axial end of each crankshaft 10, and this second crank bearing 12 b is attached to the attachment hole 7 b of the end plate portion 7. Thereby, the crankshaft 10 is rotatably supported by the board | substrate part 4a and the end plate part 7. FIG.

  Each crankshaft 10 includes a shaft main body 10c and eccentric portions 10a and 10b formed integrally with the shaft main body 10c. The 1st eccentric part 10a and the 2nd eccentric part 10b are arrange | positioned along with the axial direction between the parts supported by both crank bearings 12a and 12b. Each of the first eccentric portion 10a and the second eccentric portion 10b has a columnar shape, and both of the first eccentric portion 10a and the second eccentric portion 10b protrude radially outward from the shaft body 10c in a state of being eccentric with respect to the shaft center of the shaft body 10c. The first eccentric portion 10a and the second eccentric portion 10b are each eccentric from the shaft center by a predetermined eccentric amount, and are disposed so as to have a phase difference of a predetermined angle.

  A fitted portion 10d to which the transmission gear 20 is attached is provided at one end portion of the crankshaft 10, that is, a portion on the outer side in the axial direction of a portion attached in the attachment hole 4e of the substrate portion 4a.

  The first oscillating gear 14 is disposed in the closed space in the outer cylinder 2 and is attached to the first eccentric portion 10a of each crankshaft 10 via a first roller bearing 18a. When each crankshaft 10 rotates and the first eccentric portion 10a rotates eccentrically, the first swing gear 14 swings and rotates while meshing with the internal tooth pin 3 in conjunction with the eccentric rotation.

  The first oscillating gear 14 has a size slightly smaller than the inner diameter of the outer cylinder 2. The first swing gear 14 includes a first external tooth 14a, a central through hole 14b, a plurality (for example, three) of first eccentric portion insertion holes 14c, and a plurality (for example, three) of shaft portion insertion holes 14d. And have. The first external teeth 14 a have a wave shape that is smoothly continuous over the entire circumferential direction of the oscillating gear 14.

  The central through hole 14 b is provided in the central portion in the radial direction of the first oscillating gear 14. The input shaft 8 is inserted into the central through hole 14b with play.

  The three first eccentric portion insertion holes 14c are provided at equal intervals in the circumferential direction around the central through hole 14b in the first swing gear 14. The first eccentric portions 10a of the respective crankshafts 10 are inserted into the first eccentric portion insertion holes 14c with the first roller bearings 18a interposed therebetween.

  The three shaft portion insertion holes 14d are provided at equal intervals in the circumferential direction around the central portion through hole 14b in the first swing gear 14. Each shaft portion insertion hole 14d is disposed at a position between the three first eccentric portion insertion holes 14c in the circumferential direction. The corresponding shaft portion 4c is inserted into each shaft portion insertion hole 14d with play.

  The second oscillating gear 16 is disposed in the closed space in the outer cylinder 2 and is attached to the second eccentric portion 10b of each crankshaft 10 via a second roller bearing 18b. The first oscillating gear 14 and the second oscillating gear 16 are provided side by side in the axial direction corresponding to the arrangement of the first eccentric portion 10a and the second eccentric portion 10b. When each crankshaft 10 rotates and the second eccentric portion 10b rotates eccentrically, the second swinging gear 16 swings and rotates while meshing with the internal tooth pin 3 in conjunction with the eccentric rotation.

  The second oscillating gear 16 has a size slightly smaller than the inner diameter of the outer cylinder 2 and has the same configuration as the first oscillating gear 14. That is, the second oscillating gear 16 includes a second external tooth 16a, a central through hole 16b, a plurality of (for example, three) second eccentric portion insertion holes 16c, and a plurality of (for example, three) shaft portion insertion holes 16d. Have. These have the same structure as the first external teeth 14a, the central through hole 14b, the plurality of first eccentric portion insertion holes 14c, and the plurality of shaft portion insertion holes 14d of the first swing gear 14. The second eccentric portion 10b of the crankshaft 10 is inserted into each second eccentric portion insertion hole 16c with the second roller bearing 18b interposed therebetween.

  Each transmission gear 20 transmits the rotation of the input gear 8a to the corresponding crankshaft 10. Each transmission gear 20 is externally fitted to a fitted portion 10d provided at one end of the corresponding shaft body 10c of the crankshaft 10. Each transmission gear 20 rotates integrally with the crankshaft 10 about the same axis as the rotation axis of the crankshaft 10. Each transmission gear 20 has external teeth 20a that mesh with the input gear 8a.

  Here, the material which comprises the carrier 4 and the outer cylinder 2 is demonstrated.

  The base portion 5 of the carrier 4, that is, the substrate portion 4a and the shaft portion 4c, and the outer cylinder 2 are each made of aluminum or an aluminum alloy. The end plate portion 7 of the carrier 4 is also made of aluminum or an aluminum alloy. On the other hand, the bolt 9 that fastens the base portion 5 and the end plate portion 7 is made of an iron-based material such as stainless steel or chrome molybdenum steel. In addition, about the base 5, it is not restricted to what is comprised with aluminum or aluminum alloy, It replaces with this, and a material with a longitudinal elastic modulus lower than the longitudinal elastic modulus of an iron-type material, such as a fiber reinforced plastic and a magnesium alloy It only has to be configured.

  As described above, in the gear device 1 of the present embodiment, the shaft 4c of the base 5 that constitutes the carrier 4 and is formed with the fastening hole 4f to which the bolt 9 is fastened is made of aluminum or aluminum alloy. The bolt 9 is made of an iron-based material. For this reason, the shaft portion 4 c of the base portion 5 is softer than the bolt 9. Therefore, when the bolt 9 inserted into the bolt insertion hole 7c of the end plate portion 7 is screwed into the fastening hole f4 of the shaft portion 4c, the thread of the fastening hole 4f is easily elastically deformed. For this reason, even if there is a part where the pitch of the screw thread is slightly different due to a processing error, the strong part of the screw thread of the fastening hole 4f is elastically deformed, so that the entire axial direction of the screw is The screws can be evenly engaged with each other. Therefore, it is possible to avoid a situation in which the screw thread of the bolt 9 and the screw thread of the fastening hole are engaged with each other, and the bolt 9 is prevented from loosening when the carrier 4 receives an impact. can do.

  In the present embodiment, the outer cylinder 2 is also made of aluminum or aluminum alloy, so that the weight of the gear device 1 can be reduced. Further, it can be made less susceptible to the influence of a magnetic field. Moreover, since the heat transfer performance of the outer cylinder 2 can be improved, the heat inside the outer cylinder 2 can be easily released. Therefore, the temperature rise of the rocking gears 14 and 16 can be suppressed, and the thermal expansion of the rocking gears 14 and 16 can be suppressed. As a result, an increase in the surface pressure of the tooth portions 14a and 16a of the oscillating gears 14 and 16 can be suppressed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the two swing gears 14 and 16 are provided. However, the present invention is not limited to this. For example, a configuration in which one oscillating gear is provided or a configuration in which three or more oscillating gears are provided may be employed.

  In the above embodiment, the input shaft 8 is disposed at the center of the carrier 4 and the plurality of crankshafts 10 are disposed around the input shaft 8. However, the present invention is not limited to this. For example, a center crank type in which the crankshaft 10 is disposed at the center of the carrier 4 may be employed. In this case, as long as the input shaft 8 is provided so as to mesh with the transmission gear 20 attached to the crankshaft 10, the input shaft 8 may be disposed at any position.

DESCRIPTION OF SYMBOLS 1 Eccentric rocking gear apparatus 2 Outer cylinder 3 Internal tooth pin 4 Carrier 4a Base plate part 4c Shaft part 4f Fastening hole 5 Base 6 Main bearing 7 End plate part 7c Bolt insertion hole 9 Bolt 10 Crankshaft 10a 1st eccentric part 10b 1st 2 Eccentric part 12a First crank bearing 12b Second crank bearing 10c Shaft body 14 First swing gear 14a External tooth 14c Eccentric part insertion hole 16 Second swing gear 16a External tooth 16c Eccentric part insertion hole

Claims (3)

A gear device that transmits a driving force by converting a rotational speed at a predetermined rotational speed ratio between a first member and a second member,
An eccentric part,
An oscillating gear having an insertion hole into which the eccentric part is inserted and having a tooth part;
An outer cylinder configured to be attachable to one of the first member and the second member, and having an inner tooth that meshes with the tooth portion of the swing gear;
A carrier configured to be attachable to the other of the first member and the second member,
The carrier has a base portion in which a fastening hole is formed, an end plate portion in which an insertion hole is formed, and a bolt that is inserted into the insertion hole and fastened to the fastening hole,
The bolt is made of an iron-based material, and the base is made of a material whose longitudinal elastic modulus is lower than the longitudinal elastic modulus of the iron-based material,
An eccentric oscillating gear device in which the carrier and the outer cylinder rotate relative to each other as the oscillating gear oscillates while meshing with the inner teeth as the eccentric portion rotates.   The eccentric oscillating gear device according to claim 1, wherein the base is made of aluminum or an aluminum alloy.   The eccentric oscillating gear device according to claim 1 or 2, wherein the outer cylinder is made of aluminum or aluminum alloy.

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