JP2011064265A - Mounting structure of reduction gear, and method for manufacturing reduction gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of a reduction gear to a mounted body that can suppress vibration in driving the reduction gear, and a method for manufacturing a reduction gear that can suppress vibration in driving the reduction gear. <P>SOLUTION: The mounting structure of the reduction gear is constituted such that a stud bolt 35 projected from the end face on the motor 21 side in a circular spline 33 is inserted through a through-hole 23b formed to insert the stud bolt 35 in a motor plate 23. A nut 36 is fastened to the tip of the stud bolt 35 to fix the circular spline 33 to the motor plate 23. A press-fitting part of the stud bolt 35 is pressed into a bolt fixing hole formed on the end face on the motor 21 side of the circular spline 33. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a structure for attaching a reduction gear to a frame or the like provided in a robot, and a method of manufacturing the reduction gear.

  As this type of structure, there is a structure in which a harmonic drive (registered trademark, hereinafter the same) speed reducer is fixed to a frame (attachment body) of an arm provided in a robot by bolting (for example, see Patent Document 1). In such a structure, a through hole is generally formed in the circular spline of the speed reducer, and a female thread is formed in the arm frame by tapping. The circular spline is fixed to the frame by inserting a bolt into the through hole of the circular spline and tightening the male screw of the bolt to the female screw of the frame.

Japanese Patent No. 3801959

  By the way, in the mounting structure of the speed reducer as described above, the present inventors have found that minute vibrations are generated when the speed reducer is driven even though each member of the speed reducer is manufactured within the tolerance range. confirmed. As a result of intensive studies by the inventors of the present application, it has been found that the inner peripheral teeth of the circular spline and the outer peripheral teeth of the flexspline are not smoothly meshed as a cause of this minute vibration.

  The present invention has been made in view of such circumstances, and a main object of the present invention is to provide a speed reducer mounting structure capable of suppressing vibration during driving of the speed reducer in a structure in which the speed reducer is mounted on an attached body. It is what. Another object of the present invention is to provide a speed reducer manufacturing method capable of suppressing vibration during drive of the speed reducer.

  The present invention employs the following means in order to solve the above problems.

  As a result of intensive studies by the inventors of the present application, it has been found that in the conventional structure, when the inner teeth of the circular spline and the outer teeth of the flexspline are not smoothly meshed with each other, a minute distortion occurs in the circular spline. It was done. Accordingly, when focusing attention on the structure for mounting the reduction gear to the mounted body, the inventors have thought that there is a problem with the conventional mounting structure in which the circular spline is sandwiched and fixed between the mounted body and the head of the bolt. That is, in the conventional mounting structure, since the bolt tightening load acts on both sides of the circular spline, it is considered that minute distortion occurs in the circular spline.

  In this regard, the first invention provides a wave generator having an elliptical cam, a flex spline that has outer teeth formed on the outer peripheral portion and located outside the wave generator, and an inner peripheral portion that has more inner teeth than the outer teeth. A structure comprising: a circular spline formed with teeth and positioned outside the flexspline; and a wave gear reducer in which the external teeth of the flexspline and the internal teeth of the circular spline mesh with each other. The circular spline is provided with a protruding portion that protrudes from a predetermined surface perpendicular to the central axis thereof, and a male screw portion is formed on the protruding portion, and is provided corresponding to the protruding portion in the mounted body. The protruding portion is inserted into the through hole, and the male screw portion is tightened with a nut.

  According to the said structure, the protrusion part made to protrude in the predetermined surface orthogonal to the center axis line in the said circular spline is penetrated by the through-hole provided corresponding to the said protrusion part in the said to-be-attached body. And the circular spline is being fixed to the to-be-attached body by tightening the external thread part formed in the protrusion part with a nut. For this reason, the circular spline has a structure in which the tightening load acts only on one surface of the mounting portion, unlike the structure in which the tightening load acts on both surfaces of the mounting portion attached to the mounted body. Therefore, the occurrence of minute distortion in the circular spline is suppressed. As a result, the inventors of the present application have confirmed that the inner teeth of the circular spline and the outer teeth of the flexspline are smoothly meshed, and the vibration when the speed reducer is driven is suppressed.

  Note that in a structure in which a tightening load acts on both surfaces of the mounting portion, there is a risk that flash or the like may be caught on both surfaces of the mounting portion. When a flash or the like is sandwiched in the mounting portion, a gap is generated in the mounting portion, or the circular spline is distorted in the mounting portion, which causes vibration when the speed reducer is driven. On the other hand, in a structure in which a tightening load acts only on one side of the mounting portion, there is a possibility that a flash or the like may be caught only on one side of the mounting portion. For this reason, it can suppress that a flash etc. are pinched | interposed in the said attachment part. Therefore, it is possible to suppress the occurrence of vibration due to flash or the like at the portion where the circular spline is fixed to the mounted body.

  In the structure in which the protruding portion is formed on a predetermined surface of the circular spline by tightening one male screw to the female screw provided on the circular spline using the studs with male screws cut at both ends, the female screw is formed on the circular spline. There is a risk of flashing.

  In this regard, in the second invention, in the first invention, an implanted bolt having a press-fit portion at one end is used, and the press-fit portion of the implanted bolt is press-fitted into a hole provided in the predetermined surface of the circular spline. Thus, the protrusion is provided on the predetermined surface of the circular spline. Therefore, since it can suppress that a flash arises in the part which provides a projection part in the predetermined surface of a circular spline, it can further suppress that the vibration resulting from a flash generate | occur | produces.

  According to a third invention, in the first or second invention, the speed reducer is accommodated in a housing having a speed reducer accommodating portion, and in this state, the housing or a fixing member fixed to the housing is attached to the attached body. The speed reducer is attached to the housing or the fixing member, and the through hole is formed in the housing or the fixing member, and the protrusion is provided in the circular spline so as to extend to the outside of the housing. The projecting portion is inserted into the through hole, and the male screw portion is tightened with a nut at an outer portion of the housing.

  According to the said structure, a nut can be fastened from the housing outer side to the external thread part of the protrusion part front-end | tip, and the assembly workability | operativity of a reduction gear can be improved. In other words, adjustment of the meshing state between the flexspline and the circular spline can be performed in a state where the speed reducer is accommodated in the speed reducer accommodating portion of the housing and the nut is fastened to the male screw portion of the protruding portion. Further, according to the above-described configuration, it is possible to adjust the meshing state between the flexspline and the circular spline without removing the reduction gear from the housing even during maintenance after the reduction gear has been assembled.

  According to a fourth invention, in any one of the first to third inventions, the through hole is formed so that a predetermined gap is formed between the outer peripheral surface of the protrusion and the inner peripheral surface of the through hole. The opening dimension is set to a predetermined dimension larger than the outer dimension of the protrusion.

  According to the above configuration, since a predetermined gap is formed between the outer peripheral surface of the protruding portion and the inner peripheral surface of the through hole, the relative position of the circular spline is adjusted with the circular spline attached to the mounted body. can do. Therefore, when the circular spline is fixed to the mounted body, the center axis of the wave generator, the flexspline, and the circular spline can be made to coincide with each other with high accuracy.

  Furthermore, even if a flash is generated at a portion where the protruding portion is provided on the predetermined surface of the circular spline, the flash can be accommodated in the gap between the outer peripheral surface of the protruding portion and the inner peripheral surface of the through hole. As a result, it is possible to further suppress the occurrence of vibration due to the flash at the portion where the circular spline is fixed to the mounted body.

According to a fifth aspect of the present invention, there is provided a wave generator having an elliptical cam, a flex spline formed on the outer periphery of the outer teeth and positioned outside the wave generator, and inner teeth more than the outer teeth on the inner periphery. And a circular spline positioned outside the flexspline, and a wave gear reducer in which the external teeth of the flexspline and the internal teeth of the circular spline mesh with each other, the central axis of the circular spline being Projecting to a predetermined surface orthogonal to the first step to form a projecting portion having a male screw portion at the tip, and a second step of providing the internal teeth on the circular spline after the first step,
It is characterized by providing.

  According to the above process, as the first process, the circular spline is protruded on a predetermined surface orthogonal to the central axis thereof, and a protruding part having a male screw part at the tip is formed. Then, after the first step, the internal teeth are provided on the circular spline. For this reason, even if distortion occurs in the circular spline when the protrusion is provided on the predetermined surface of the circular spline, the internal teeth can be provided in the circular spline without being affected by the distortion. As a result, the inner teeth of the circular spline and the outer teeth of the flexspline can be smoothly meshed.

  According to a sixth aspect, in the fifth aspect, the first step includes the step of providing a hole in the predetermined surface of the circular spline and the press-fitting portion of the stud bolt having a press-fitting portion at one end thereof. And a process.

  According to the above process, as described in the second aspect of the invention, it is possible to suppress the occurrence of burrs in the portion where the projecting portion is provided on the predetermined surface of the circular spline, as compared with the process of cutting the female thread in the circular spline. . Therefore, it is possible to suppress the occurrence of vibration due to the flash when the speed reducer is driven.

Sectional drawing which shows the internal structure in the joint part of a robot apparatus. The exploded sectional view of a reduction gear unit. The front view which shows the outline | summary of a robot apparatus. The figure which shows the assembly | attachment procedure of a reduction gear unit.

  Hereinafter, an embodiment in which the present invention is embodied as a vertical articulated robot will be described with reference to the drawings. The robot of this embodiment is used in an assembly system such as a machine assembly factory as an industrial robot device, for example.

  First, an outline of the robot apparatus 10 will be described with reference to FIG. As shown in FIG. 3, the robot apparatus 10 has six axes having a first axis J1, a second axis J2, a third axis J3, a fourth axis J4, a fifth axis J5, and a sixth axis J6 as rotation center axes. It is a robot, and the operation angle of each part in each axis is adjusted by driving a drive source such as a servo motor. Each servo motor can rotate in both forward and reverse directions, and each part operates with the origin position as a reference by driving the motor. In the present embodiment, the robot apparatus 10 is installed at a robot installation location such as a floor so that the first axis J1 extends in the vertical direction, and the following description will be made assuming that the vertical direction in FIG. 1 indicates the vertical direction.

  In the robot apparatus 10, the base 11 has a fixed portion 12 fixed to a floor or the like, and a rotating portion 13 provided above the fixed portion 12, and the rotating portion 13 is a first axis J1. It is possible to rotate in the horizontal direction around the center of rotation. A lower arm 15 is rotatably connected to an upper end portion of the rotating portion 13. The lower arm 15 is provided in a direction extending in the vertical direction as a basic posture, and an upper arm 16 is rotatably connected to an upper end portion thereof. The upper arm 16 is provided in a direction extending in the horizontal direction as a basic posture.

  The lower arm 15 is rotatable with respect to the rotation unit 13 about the second axis J2 extending in the horizontal direction, and rotates in the clockwise direction or the counterclockwise direction within a predetermined operation range. Operate. The upper arm 16 is rotatable with respect to the lower arm 15 about a third axis J3 extending in the horizontal direction as a rotation center, and rotates in a clockwise direction or a counterclockwise direction within a predetermined operation range. It works.

  The upper arm 16 is divided into two arm portions on the base end side and the tip end side, and the base end side is a first upper arm 16A and the tip end side is a second upper arm 16B. The first upper arm 16A is rotatably connected to the lower arm 15 as described above. On the other hand, the second upper arm 16B is rotatable in the torsional direction with respect to the first upper arm 16A with the fourth axis J4 extending in the longitudinal direction of the main upper arm 16 as a rotation center.

  A wrist portion 17 is provided at the tip of the upper arm 16 (specifically, the second upper arm 16B), and a hand portion 18 for attaching a work, a tool, or the like is provided on the wrist portion 17. The wrist portion 17 is rotatable with respect to the second upper arm 16B with a fifth axis J5 extending in the horizontal direction as a rotation center. The hand portion 18 is rotatable in the torsional direction with the sixth axis J6 being the center line as a rotation center.

  In the robot apparatus 10, a reduction mechanism for reducing the rotation of the servo motor provided on the front member side and transmitting it to the next member side is provided at the joint portion of each axis J1 to J6. Details will be described. Here, a connecting part (joint part) of both of them will be described with the front member as the rotating portion 13 of the base 11 and the next member as the lower arm 15. FIG. 1 is a cross-sectional view showing an internal structure of a connecting portion (joint portion) between the upper end portion of the rotating portion 13 and the lower arm 15 in the base 11, and this corresponds to a cross-sectional view taken along line AA in FIG. To do.

  As shown in FIG. 1, the upper end portion of the rotating portion 13 is provided so as to enter the inside of the lower arm 15, specifically, to be covered with an arm cover 15 a constituting the lower arm 15. . A connecting mechanism for connecting the rotating portion 13 and the lower arm 15 is provided in the arm cover 15a. As a basic structure, this coupling mechanism includes a motor (servo motor) 21 fixed to the rotating portion 13 side (that is, the base 11 side), and a speed reducer as a speed reducing means provided on the output shaft side of the motor 21. The unit 22 is configured. The central axis of the motor 21 and the speed reducer unit 22 is the second axis J2 described above.

  A metal motor plate (fixing member) 23 is provided on an end surface portion of the motor 21 on the output shaft side, and a reduction gear unit 22 is attached to the opposite side of the motor 21 with the motor plate 23 interposed therebetween. . The motor plate 23 has an annular shape and is fixed to a metal base frame 24 constituting the rotating portion 13 by a plurality of bolts 25. A hollow cylindrical portion 26 extending along the axial direction of the speed reducer unit 22 is formed at the distal end portion (upper end portion in the drawing) of the base frame 24, and the speed reducer unit 22 is formed inside the cylindrical portion 26. Is incorporated. The opening of the cylindrical portion 26 is different between the motor side (left side in FIG. 1) and the non-motor side (right side in FIG. 1). Is to be incorporated. The cylindrical portion 26 corresponds to a housing, and this internal space is a reduction gear housing portion. A stepped portion 26a is formed on the end surface of the cylindrical portion 26 on the motor side, and the motor plate 23 is attached so as to be fitted into the stepped portion 26a.

  Regarding the fixing of the motor plate 23 to the base frame 24, the motor plate 23 is formed with a through hole 23a penetrating in the thickness direction, and the base frame 24 opens to the contact surface side with the motor plate 23. A screw hole 24a is formed. The motor plate 23 is fixed to the base frame 24 by inserting and fastening bolts 25 into the through holes 23a and the screw holes 24a.

  Next, the configuration of the speed reducer unit 22 will be described with reference to FIG.

  The reduction gear unit 22 is configured by integrating a reduction gear having a harmonic drive (registered trademark, hereinafter the same) structure and a bearing 27 including a cross roller bearing. Note that the speed reducer of the present embodiment is a wave gear speed reducer. The speed reducer includes a wave generator 31 in which a ball bearing is assembled on the outer periphery of an elliptical cam, a thin cup-shaped flexspline (elastic gear) 32 disposed on the outer side thereof, and a rigid ring disposed on the outer side thereof. And a circular spline (internal gear) 33. A large number of external teeth 32 a are formed on the outer peripheral portion of the cup of the flex spline 32, and internal teeth 33 a having a predetermined number (for example, two) of teeth on the inner peripheral portion of the circular spline 33 than the flex spline 32. The outer teeth 32 a and the inner teeth 33 a are configured to mesh with each other at the major axis portion of the wave generator 31.

  An output shaft 21a of the motor 21 is connected to the wave generator 31 by a bolt or the like, and the wave generator 31 rotates integrally with the motor output shaft 21a as an input shaft.

  The circular spline 33 is fixed to the motor plate 23 with its motor side end surface (predetermined surface) in contact with the motor plate 23. Specifically, in the circular spline 33, a plurality of bottomed bolt fixing holes 33b are formed on the motor side end surface orthogonal to the central axis, and stud bolts (planting bolts) 35 are erected by press-fitting into the bolt fixing holes 33b. Has been. The stud bolt 35 is a press-fit stud bolt having one end (planting side) as a press-fit portion and the other end as a male screw portion. The stud bolt 35 forms a protruding portion that protrudes from the motor side end surface of the circular spline 33. In other words, the circular spline 33 is provided with stud bolts 35 extending in the direction extending to the outside of the cylindrical portion 26. Here, the stud bolt 35 is formed of a metal having a hardness higher than that of the circular spline 33. For this reason, the stud bolt 35 functions as a reinforcing member by press-fitting the stud bolt 35 into the fixing hole 33b formed in the circular spline 33. Therefore, the rigidity of the circular spline 33 can be increased.

  In addition, the structure which fastens one male screw to the female screw provided in the circular spline using the stud bolt by which the male screw was cut in the both ends instead of the structure which press-fits the press-fit part of the stud bolt 35 to the bolt fixing hole 33b is employ | adopted. You can also However, in such a configuration, there is a risk that flash may occur when the female screw is formed on the circular spline. That is, in the process of cutting the internal thread, a minute flash is likely to occur in the process of scraping the material, and even if such a small flash (for example, a flash of about several tens of μm) is sandwiched between the tightening portions of the circular spline 33, the circular spline 33 is distorted. It can be a cause. In addition, these flashes are not constant in size but have variations, and it is difficult to predict their effects.

  Further, the motor plate 23 is formed with a through hole 23b through which the stud bolt 35 is inserted. The through hole 23 b is formed as a hole having a diameter larger than the outer diameter of the stud bolt 35, that is, as a hole having some play with respect to the stud bolt 35. For this reason, it is not necessary to increase the positional accuracy when forming the through hole 23b, and surface processing of the motor plate 23 before the formation of the through hole 23b can be omitted. Then, the stud bolt 35 is inserted into the through hole 23b, the circular spline 33 is assembled to the motor plate 23, and the nut 36 is fastened to the tip of the stud bolt 35 in this state, whereby the motor plate (attachment body) ) 23, the circular spline 33 is fixed. According to such a configuration, even if a small bulge occurs due to deformation when the press-fitted portion of the stud bolt 35 is press-fitted into the bolt fixing hole 33b, the small bulge can be accommodated in the play portion.

  A thick boss portion 32b is formed on the opposite side of the flex spline 32 in the direction of the central axis of the flex spline 32, and a bearing 27 is assembled to the boss portion 32b. The bearing 27 includes an inner ring 28 and two outer rings 29, and the inner ring 28 is fixed to the boss portion 32b. More specifically, a through hole 32c is formed in the boss portion 32b, and a screw hole 28a is formed in the inner ring 28. A bolt 38 is attached to the boss portion 32b and the inner ring 28 via an attachment member 37. Is fastened. The inner ring 28 of the bearing 27 rotates integrally with the flexspline 32, and this serves as the output shaft of the speed reducer unit 22.

  Further, the inner ring 28 of the bearing 27 is formed with a screw hole 28b for connecting the inner ring 28 to the arm frame 41 (see FIG. 1). Further, the outer ring 29 of the bearing 27 has a through hole 29 a for connecting the outer ring 29 to the cylindrical portion 26 (see FIG. 1) of the base frame 24 at a position outside the cup outer periphery of the flexspline 32. Is formed. The outer diameter of the outer ring 29 is larger than the opening dimension of the cylindrical portion 26 of the base frame 24 on the side opposite to the motor.

  Returning to the description of FIG. 1, the outer ring 29 of the bearing 27 is fixed to the cylindrical portion 26 of the base frame 24 by a plurality of bolts 39. The inner ring 28 of the bearing 27 is fixed to a metal arm frame 41 constituting the lower arm 15 with a plurality of bolts 42. In this case, the lower end attachment portion of the arm frame 41 is attached to the bearing 27 so as to close the opening of the cylindrical portion 26 on the side opposite to the motor.

  Regarding the robot apparatus 10 having the above-described configuration, the operation of the joint portion between the rotating portion 13 and the lower arm 15 of the base 11 will be described. When the motor 21 is driven to rotate, the wave generator 31 rotates integrally with the motor output shaft 21a, and the rotation of the wave generator 31 is transmitted to the flexspline 32 while being decelerated at a predetermined reduction ratio. And the inner ring | wheel 28 of the bearing 27 rotates integrally with the flexspline 32, and the arm frame 41 fixed to the inner ring | wheel 28 rotates to a normal / reverse direction centering on the 2nd axis | shaft J2. Thereby, the lower arm 15 is adjusted to a desired operation angle.

  The robot system including the robot apparatus 10 includes a control device that controls the operation of the robot apparatus 10. This control device is a robot control means having a CPU and various memories, and the rotation angle of each axis and the trajectory of each part are controlled by this control device. However, the detailed explanation is omitted here.

  Next, a method for manufacturing the robot apparatus 10 will be described. Here, the processing procedure of the circular spline 33 and the assembly procedure of the reduction gear unit 22 will be described.

(1) Processing procedure of the circular spline 33 When the circular spline 33 is constituted by a cast product, first, a coarse casting material of the circular spline 33 is manufactured, and the outer surface of the casting coarse material is rough processed. Next, the outer peripheral surface of the circular spline 33 after rough machining is machined. Further, one end face which is a contact surface with the motor plate 23 is processed, and bottomed bolt fixing holes 33b are formed at a plurality of positions on the end surface side (motor plate contact surface side).

  Next, the stud bolt 35 is press-fitted into the bolt fixing hole 33b, and the stud bolt 35 is integrated with the circular spline 33 (first step). As a result, a plurality of stud bolts 35 extending in the same direction as the central axis of the circular spline 33 are erected on one end face of the circular spline 33. Thereafter, teeth are processed on the inner peripheral portion of the circular spline 33 to form the inner teeth 33a (second step). In such a case, even if the circular spline 33 is distorted when the stud bolt 35 is press-fitted into the bolt fixing hole 33b, the internal teeth 33a are provided on the inner peripheral portion of the circular spline 33 so as not to be affected by the distortion. Can be formed. Further, since the tooth machining is performed after the stud bolt 35 is press-fitted, it is possible to suppress inconveniences such as the internal teeth 33a being distorted due to another process after the tooth machining.

(2) Assembly procedure of reduction gear unit 22 The assembly procedure of the reduction gear unit 22 will be described with reference to FIG.

  First, the flexspline 32 and the bearing 27 are integrated to assemble the output side assembly A1 of the reduction gear unit 22, and the motor 21, the motor plate 23, and the wave generator 31 are integrated to form the reduction gear unit 22. The input side assembly A2 is assembled. For example, a base frame 24 made of a cast product is prepared. The base frame 24 is not directly connected to the circular spline 33 and does not contact the end surface (end surface orthogonal to the central axis) of the circular spline 33. There is no processing.

  Then, as shown in FIG. 4 (a), the output side assembly A1 (flexible) of the reduction gear unit 22 is inserted into the cylindrical portion 26 of the base frame 24 from the motor side of the cylindrical portion 26 (from the end with the larger end opening). And the output side assembly A1 is fixed to the cylindrical portion 26 by a bolt 39.

  On the other hand, as shown in FIG. 4B, the circular spline 33 is assembled to the input side assembly A2 of the reduction gear unit 22 (an integrated body of the motor 21, the motor plate 23, and the wave generator 31). Specifically, the stud bolt 35 integrated with the circular spline 33 is inserted into the through hole 23 b of the motor plate 23, and the nut 36 is fastened to the tip end portion of the stud bolt 35 to fix the motor plate 23 to the motor plate 23. The circular spline 33 is fixed. At this time, the nut 36 is temporarily tightened to allow a slight movement of the circular spline 33.

  Thereafter, as shown in FIG. 4C, the input side of the speed reducer unit 22 in which a circular spline 33 is temporarily fixed to the base frame 24 in a state where the output side assembly A1 of the speed reducer unit 22 is assembled. Assemble the assembly A2. At this time, the input side assembly A2 is assembled from the same direction as the direction in which the output side assembly A1 is assembled to the base frame 24.

  In detail, the flex spline 32 is inserted into the gap between the ball bearing on the outer periphery of the wave generator 31 and the internal teeth 33a of the circular spline 33, and the external teeth 32a of the flex spline 32 and the internal teeth 33a of the circular spline 33 are Bite. Then, the motor plate 23 is fixed to the base frame 24 by fastening the bolts 25.

  Thereafter, the meshing adjustment between the external teeth 32 a of the flexspline 32 and the internal teeth 33 a of the circular spline 33 is performed. At this time, the circular spline 33 is temporarily fixed and is allowed to move slightly. In the state of FIG. 4C, the tip end portion of the stud bolt 35 (that is, the temporarily tightened nut 36) is located outside the cylindrical portion 26 of the base frame 24, so that the nut 36 can be tightened. It has become. Therefore, meshing adjustment and centering adjustment of each tooth are performed while rotating the motor output shaft 21a at a low rotation. In addition, it is good to rotate the motor 21 by giving an electric signal from the outside, or to rotate the motor output shaft 21a manually. By the above adjustment work, the centering accuracy of the wave generator 31, the flex spline 32 and the circular spline 33 is improved.

  Then, after completing the meshing adjustment and the centering adjustment, the nut 36 is finally tightened. Thereby, the assembly of the motor 21 and the speed reducer unit 22 to the base frame 24 is completed. At this time, since the stud bolt 35 is partially embedded in the circular spline 33 and integrated, the tightening load of the nut 36 does not act on the end surface opposite to the bolt protruding side in the circular spline 33. The tightening load of the nut 36 acts only on the end surface on the bolt protruding side. Therefore, when the circular spline 33 is tightened and fixed as the nut 36 is tightened, it is possible to suppress the distortion of the internal teeth 33a of the circular spline 33 due to the tightening.

  After the reduction gear unit 22 has been assembled as described above, the lower arm 15 is connected to the base 11. At this time, the lower arm 15 is connected to the reduction gear unit 22 by fixing the arm frame 41 to the inner ring 28 of the bearing 27 with the bolts 42.

  The embodiment described above has the following advantages.

  The stud bolt 35 protruding from the motor side end face in the circular spline 33 is inserted into the through hole 23 b formed in the motor plate 23 for inserting the stud bolt 35. The circular spline 33 is fixed to the motor plate 23 by fastening the nut 36 to the tip of the stud bolt 35. Therefore, the circular spline 33 has a structure in which a tightening load acts only on one surface of the attachment portion attached to the motor plate 23, and the occurrence of minute distortion in the circular spline 33 is suppressed. As a result, the inner teeth 33a of the circular spline 33 and the outer teeth 32a of the flex spline 32 are smoothly meshed with each other, and vibration during driving of the reduction gear unit 22 can be suppressed. Further, in a structure in which a tightening load is applied only to one side of the mounting portion, only one side of the mounting portion may be caught by a flash or the like. For this reason, it can suppress that a flash etc. are pinched | interposed in the said attachment part.

  The nut 36 can be tightened from the outside of the cylindrical portion 26 to the tip end portion of the stud bolt 35, and the assembling workability of the reduction gear unit 22 can be improved. That is, in the state where the reduction gear unit 22 is accommodated in the internal space of the cylindrical portion 26 and the nut 36 is fastened to the tip end portion of the stud bolt 35, the engagement state of the flexspline 32 and the circular spline 33 is adjusted. Can be implemented. Further, even during maintenance after the reduction gear unit 22 has been assembled, the meshing state of the flexspline 32 and the circular spline 33 can be adjusted without removing the reduction gear unit 22 from the cylindrical portion 26. .

  Since the stud bolt 35 is erected by press-fitting into the bolt fixing hole 33b, the portion where the stud bolt 35 is provided is more burr than the configuration in which the female screw is cut into the circular spline 33 and the male screw of the stud bolt is tightened. This can be suppressed. In particular, in an articulated robot, there is a possibility that the displacement of the trajectory may increase in the hand portion 18 that is the tip of the arm due to accumulation of minute distortions of the circular spline 33 caused by such flash at each joint portion. Therefore, the effect by suppressing the minute distortion of the circular spline 33 becomes remarkable.

  It is not limited to the said embodiment, For example, it can also implement as follows.

  In the above-described embodiment, the stud bolt 35 protruding to the motor side is provided in the circular spline 33 and the stud bolt 35 is coupled to the motor plate 23. However, this is changed, and the circular spline 33 is arranged on the counter-motor side. A protruding stud bolt 35 may be provided, and the stud bolt 35 may be coupled to the base frame 24. In this case, a part of the base frame 24 is used as a contact portion that contacts the end surface of the circular spline 33, and the stud bolt 35 is inserted into the through hole formed in the contact portion, and at the front end side of the stud bolt 35. Tighten the nut. Thereby, the circular spline 33 can be fixed to the base frame 24.

  In the above configuration, since the circular spline 33 and the outer ring 29 of the bearing 27 are fixed to the base frame 24, the output side assembly of the reduction gear unit 22 includes the circular spline 33. Further, the bolt insertion direction when the outer ring 29 of the bearing 27 is fixed to the base frame 24 is reversed (inserted from the non-motor side), and the bolt is formed by the outer ring 29 inside the cylindrical portion 26 or further by a nut inside the same. It is good to tighten.

  In the above embodiment, the output side assembly A1 and the input side assembly A2 of the reduction gear unit 22 are assembled from the same direction with respect to the cylindrical portion 26 of the base frame 24 (see FIG. 4). It is good also as a structure which changes and assembles each assembly A1, A2 from a different direction, respectively. Specifically, as in FIG. 4C, the input side assembly A2 is assembled to the base frame 24 from the motor side of the cylindrical portion 26, while the output side assembly A1 is connected to the end portion of the cylindrical portion 26 on the opposite motor side. It is good to accommodate and arrange in the cylindrical portion 26 from the opening. In this case, the end opening of the cylindrical portion 26 on the side opposite to the motor is formed to a size that allows the output side assembly A1 to pass through, and a bolt for fixing the outer ring 29 of the bearing 27 is inserted from the side opposite to the motor. It may be fastened to a part of the base frame 24.

  In the above embodiment, as the stud bolt 35, a press-fit stud bolt in which one end (planting side) is a press-fit portion and the other end is a male screw portion is used. A structure in which a male screw is formed may be used. Even in this case, the tightening load of the nut 36 can be applied only to the end surface on the bolt protruding side.

  In the above embodiment, the method of fixing the stud bolt 35 is used as a configuration in which the projecting portion is provided on one end face of the circular spline 33. However, in addition to this, the circular spline 33 is obtained by grinding a cast product or a forged product. It is also possible to provide the protrusions integrally with each other.

  -It is also possible to adopt a configuration without cross roller bearings as the reducer unit.

  In the above embodiment, the robot apparatus is embodied as a 6-axis vertical articulated robot, but can be embodied as a robot apparatus other than 6 axes. It can also be embodied as a horizontal articulated robot.

  DESCRIPTION OF SYMBOLS 21 ... Motor, 22 ... Reduction gear unit, 23 ... Motor plate, 24 ... Base frame, 31 ... Wave generator, 32 ... Flex spline, 33 ... Circular spline, 35 ... Stud bolt, 36 ... Nut

Claims (6)

A wave generator having an elliptical cam, an outer tooth formed on the outer peripheral portion and a flexspline positioned outside the wave generator, and an inner peripheral portion formed with more inner teeth than the outer teeth and the outer side of the flexspline A wave gear type speed reducer in which the external teeth of the flexspline and the internal teeth of the circular spline mesh with each other.
The circular spline is provided with a protruding portion that protrudes from a predetermined surface perpendicular to the central axis thereof, and a male screw portion is formed on the protruding portion, and is provided corresponding to the protruding portion in the mounted body. The speed reducer mounting structure, wherein the protruding portion is inserted into a through hole, and the male screw portion is tightened with a nut.   The projecting part is provided on the predetermined surface of the circular spline by using an implanted bolt having a press-fitting part at one end, and the press-fitted part of the implanting bolt is press-fitted into a hole provided on the predetermined surface of the circular spline. The speed reducer mounting structure according to claim 1, wherein the speed reducer mounting structure is provided. The speed reducer is accommodated in a housing having a speed reducer accommodating portion, and in that state, the housing or the fixing member fixed to the housing is used as the mounted body to attach the speed reducer,
The housing or the fixing member is formed with the through-hole, and the circular spline is provided with the protrusion in a direction extending to the outside of the housing, and the protrusion is inserted into the through-hole. The speed reducer mounting structure according to claim 1 or 2, wherein the male screw portion is tightened by a nut at an outer portion of the housing.   The opening dimension of the through hole is set to a predetermined dimension larger than the outer dimension of the projecting part so that a predetermined gap is formed between the outer peripheral surface of the projecting part and the inner peripheral surface of the through hole. The speed reducer mounting structure according to any one of claims 1 to 3, wherein: A wave generator having an elliptical cam, an outer tooth formed on the outer peripheral portion and a flexspline positioned outside the wave generator, and an inner peripheral portion formed with more inner teeth than the outer teeth and the outer side of the flexspline A wave spur reducer, wherein the external teeth of the flexspline mesh with the internal teeth of the circular spline.
A first step of projecting a predetermined surface perpendicular to the central axis of the circular spline to form a projecting portion having a male screw portion at a tip portion;
A second step of providing the internal teeth on the circular spline after the first step;
A speed reducer manufacturing method comprising:   The said 1st process includes the process of providing a hole in the said predetermined surface of the said circular spline, and the process of press-fitting the said press-fit part of the implantation bolt which has a press-fit part in an end to the said hole. A manufacturing method of the reduction gear described in 1.

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