JP2013064425A - Wave gear reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which can reduce an assembling error of a wave gear reducer incorporated in a robot.SOLUTION: The wave gear reducer 22 has a wave generator 31, a flexspline 32, and a circular spline 33. The circular spline 33 is put between a fixed plate 23 and a chassis 24 and fixed at the chassis 24 by fastening the fixed plate 23 to the chassis 24 with a bolt 35. At a contact portion for the fixed plate 23 of the circular spline 33 and at a contact portion for the circular spline 33 of the fixed plate 23, inclined portions having inclined faces inclining in circumferential directions and step portions provided at edges of the inclined faces are formed on the whole circumference of the circular spline, the inclined faces of the inclined portions are brought into surface contact with each other, and furthermore the step portions of the inclined portions are engaged with each other.

Description

  The present invention relates to a wave gear reducer attached to a robot casing.

  The industrial robot incorporates a motor and a speed reducer for driving the joint. In order to obtain a large torque capacity, for example, a wave gear reducer is employed as a reduction gear for a robot (see Patent Document 1). As is well known, a wave gear reducer includes a wave generator having a ball bearing on the outer periphery of an elliptical cam, a flex spline that is a cup-shaped metal elastic body with outer teeth formed on the outer periphery of an opening, and a rigid annular ring. And a circular spline with inner teeth engraved on the inner periphery.

  Generally, the circular spline is fastened to the robot casing by about ten bolts. However, for example, if there is uneven surface pressure on the seating surfaces of these bolts, the circular spline is deformed, resulting in an assembly error. Such an assembly error causes a vibration of the robot, which may affect a defect rate of a product produced by the robot.

JP 2009-257409 A

  In view of the above problems, the problem to be solved by the present invention is to provide a technique capable of reducing an assembly error of a wave gear reducer incorporated in a robot.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A wave gear reducer attached to a housing of a robot, having a wave generator having an elliptical cam, and a cup-shaped cup having outer teeth formed on the outer peripheral portion and disposed outside the wave generator A flex-spline, and a ring-shaped circular spline in which more internal teeth than the external teeth are formed on an inner peripheral portion, and the flexspline is disposed on the inner peripheral portion, the circular spline including a fixed plate The fixed portion is fixed to the casing by being clamped between the casing and the fixing plate with a bolt, and the circular spline is in contact with the fixing plate, and the circular plate of the fixing plate is fixed to the casing. The contact portion with respect to the spline includes an inclined surface inclined toward the circumferential direction and a stepped portion provided at an end of the inclined surface, respectively. The inclined portion is formed over the entire circumference of the circular spline, and the inclined surface of the inclined portion of the circular spline and the inclined surface of the inclined portion of the fixed plate are in surface contact, and the inclined portion of the circular spline is inclined. A wave gear reducer in which a stepped portion of the portion and a stepped portion of the inclined portion of the fixed plate are engaged.

  With such a configuration, the inclined surface of the inclined portion of the circular spline and the inclined surface of the inclined portion of the fixed plate are brought into surface contact, and the step portion of the inclined portion of the circular spline and the step portion of the inclined portion of the fixed plate are brought into contact with each other. By engaging, the circular spline is fixed to the robot casing. Therefore, it is not necessary to fix the circular spline to the casing with the bolts, so that the assembly error of the wave gear reducer can be reduced. As a result, it is possible to suppress the vibration and noise of the robot. Further, since the inclined portion of the circular spline and the inclined portion of the fixed plate are formed over the entire circumference of the circular spline, the pressing force of the fixed plate against the circular spline is evenly distributed. Therefore, even if the circular spline is deformed by this pressing force, the circular spline is deformed as a whole, and local deformation (deformation in which the circular spline undulates) is suppressed. As a result, it is possible to suppress the occurrence of vibration and noise when the tightening torque of the bolt at the time of fastening of the fixing plate is increased as a whole.

[Application Example 2] The wave gear reducer according to Application Example 1, wherein the circular spline and the fixed plate are each provided with one inclined portion.

  It is also possible to provide a plurality of inclined portions for each of the circular spline and the fixed plate. However, if the number of the inclined portions is one as in the above configuration, the processing accuracy of the circular spline and the fixed plate is improved, so that the assembly error can be further reduced.

Application Example 3 The wave gear reducer according to Application Example 1 or Application Example 2, wherein the circular spline and the fixed plate are formed of the same material.

  In this way, if the circular spline and the fixed plate are formed of the same material, the coefficient of thermal expansion can be made the same. Therefore, even if the fixed plate is thermally expanded by heat from a motor or the like, the circular spline is affected by the thermal expansion. Can be made to follow. Therefore, vibration and noise can be further reduced.

  In addition, this invention is not restricted to the structure as a wave gear reducer mentioned above, For example, it can be comprised also as a manufacturing method of a wave gear reducer.

It is explanatory drawing which shows schematic structure of a wave gear reducer. It is the perspective view which looked at the fixed plate from the upper surface side. It is the perspective view which looked at the circular spline from the lower surface side. It is a figure which shows the example of the fixed plate which has a some inclination part. It is a figure which shows the example of the circular spline which has a some inclination part.

A. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a wave gear reducer as an embodiment of the present invention. The wave gear reducer 22 is a device for driving the joint of the robot together with the motor 21, and includes a wave generator 31, a flex spline 32, and a circular spline 33. Hereinafter, the vertical direction in FIG. 1 will be described as the vertical direction of the wave gear reducer 22.

  The wave gear reducer 22 is disposed in a hollow cylindrical portion 25 provided in the robot casing 24. In the cylindrical portion 25, a first step portion 25a, a second step portion 25b, and a third step portion 25c are formed from the upper side to the lower side, and are formed so that the diameter increases in this order. An annular first plane portion 24a is formed between the first step portion 25a and the second step portion 25b, and an annular second plane portion 24b is formed between the second step portion 25b and the third step portion 25c. Is formed.

  The wave generator 31 is configured by assembling a ball bearing 31b on the outer periphery of an elliptical cam 13a. The flex spline 32 is a metal elastic body having a thin cup-like shape, and an opening at a lower portion thereof is disposed outside the wave generator 31. The circular spline 33 is a rigid annular member, and is disposed outside the opening of the flexspline 32. A large number of external teeth 32 a are formed on the outer periphery of the opening of the flexspline 32, and an internal tooth having a predetermined number (for example, two) of teeth on the inner periphery of the circular spline 33 than the external teeth 32 a of the flexspline 32. 33a is formed. The external teeth 32a and the internal teeth 33a mesh with each other at the long axis portion of the elliptical wave generator 31.

  The wave generator 31 is disposed in the second step portion 25 b of the cylindrical portion 25. An output shaft 21a of the motor 21 is connected to the wave generator 31 by a bolt 21b. The wave generator 31 rotates together with the rotating shaft 21a of the motor 21 using the rotating shaft 21a of the motor 21 as an input shaft.

  In the flex spline 32, the lower opening in which the external teeth 32a are formed is disposed in the second step portion 25b of the cylindrical portion 25, and the upper portion thereof is in the first step portion 25a of the cylindrical portion 25. Placed in. A thick boss portion 32 c is formed on the cup-shaped bottom portion 32 b of the flexspline 32. An output shaft (not shown) is fastened to the boss portion 32 c by a bolt 38 via an attachment member 37.

  The circular spline 33 is disposed in the second step portion 25b of the cylindrical portion 25, and the upper surface is in contact with the first flat surface portion 24a. A spiral first inclined portion 331 is formed on the lower surface of the circular spline 33 over the entire circumference of the circular spline 33. The lower surface of the first inclined portion 331 is in contact with a second inclined portion 231 formed on the upper surface of the fixed plate 23 described later.

  The fixing plate 23 is a member for fixing the motor 21 to the housing 24, and is disposed on the upper end surface of the motor 21. The fixing plate 23 is disposed in the third step portion 25 c in the cylindrical portion 25, and the outer peripheral portion thereof is fastened to the second flat portion 24 b by a plurality of bolts 35. The fixed plate 23 and the circular spline 33 are formed of the same material (for example, iron).

  FIG. 2 is a perspective view of the fixed plate 23 as viewed from the upper surface side. In the fixed plate 23, a spiral second inclined portion 231 is formed at the contact portion that contacts the circular spline 33 so as to extend over the entire circumference of the circular spline 33. The second inclined portion 231 includes an inclined surface 232 that is inclined at a constant angle toward the circumferential direction CD1, and a step portion 233 provided at an end of the inclined surface 232. In the present embodiment, the step portion 233 is formed perpendicular to the lower surface of the fixed plate 23. The outer diameter W1 of the inclined portion 231 is the same as the inner diameter of the second step portion 25b of the cylindrical portion 25, and can be set to 100 mm, for example. The height H1 of the stepped portion 233 can be set to 5 mm, for example. A bolt fixing hole 35 b into which a bolt 35 for fixing the fixing plate 23 to the housing 24 is inserted is formed in the annular outer peripheral portion 23 a of the fixing plate 23. The outer diameter of the outer peripheral portion 23 a of the fixed plate 23 is formed smaller than the inner diameter of the third step portion 25 c of the cylindrical portion 25.

  FIG. 3 is a perspective view of the circular spline 33 as seen from the lower surface side. As described above, the inner teeth 33 a are formed on the inner periphery of the circular spline 33. In the circular spline 33, a spiral first inclined portion 331 is formed at a contact portion that contacts the fixed plate 23. The first inclined portion 331 includes an inclined surface 332 inclined at the same angle as the inclined surface 232 of the fixed plate 23 toward the circumferential direction CD2, and a step portion 333 provided at an end of the inclined surface 332. In the present embodiment, the stepped portion 333 is formed perpendicular to the upper surface (the lower surface in FIG. 3) of the circular spline 33. The outer diameter W2 of the inclined portion 332 is the same as the outer diameter of the inclined portion 231 of the fixed plate 23, and can be set to 100 mm, for example. The height H2 of the stepped portion 333 is the same as the height of the stepped portion 232 of the fixed plate 23, and can be set to 5 mm, for example. The height H3 of the circular spline 33 excluding the inclined portion 331 can be set to 10 mm, for example. Unlike the fixing plate 23 shown in FIG. 2, the circular spline 33 has no holes for passing bolts.

  In FIG. 1, the inclined surface 232 of the fixed plate 23 shown in FIG. 2 and the inclined surface 332 of the circular spline 33 shown in FIG. 3 are in surface contact within the second step portion 25 b of the cylindrical portion 25. The state where the stepped portion 233 of the fixed plate 23 and the stepped portion 333 of the circular spline 33 are engaged with each other (shown in an engaged state) is shown. In the present embodiment, the circular spline 33 is fixed to the casing 24 by the first inclined portion 331 of the circular spline 33 and the second inclined portion 231 of the fixing plate 23 thus contacting with no gap. .

B. Production method:
The wave gear reducer 22 of the present embodiment described above can be manufactured by, for example, the following procedures (1) to (4).

(1) The output side assembly is assembled by integrating the flexspline 32 and the output shaft with the attachment member 37 and the bolt 38. Further, the wave generator 31 is fixed to the rotating shaft 21a of the motor 21 having the fixing plate 23 with the bolt 21b, and the input side assembly is assembled.

(2) The circular spline 33 is inserted into the second step portion 25b of the casing 24, and the first inclined portion 331 of the circular spline 33 and the second inclined portion 231 of the fixed plate 23 are spaced as shown in FIG. The fixing plate 23 of the input side assembly is inserted into the third step portion 25c of the cylindrical portion 25 so as to come into contact with each other.

(3) The circular spline 33 is fixed to the casing 24 together with the input side assembly by fastening the fixing plate 23 to the second flat surface portion 24b of the casing 24 with the bolts 35.

(4) The external teeth 32a of the flex spline 32 of the output side assembly are inserted into the gap between the internal teeth 33a of the circular spline 33 and the outer periphery of the wave generator 31 arranged on the inside thereof, and the output side assembly is inserted into the housing 24. It fixes to the 1st step part 25a side.

C. effect:
In the wave gear reducer 22 of the present embodiment described above, the circular spline 33 is provided between the fixing plate 23 for fixing the motor 21 and the first flat portion 24a of the housing 24 without using bolts. It is pinched and fixed by these being brought into surface contact with each other. Therefore, there is no possibility that the circular spline 33 is deformed due to uneven surface pressure on the seat surface of the bolt as in the prior art. Therefore, it is possible to reduce the assembly error of the wave gear reducer 22, and as a result, it is possible to suppress the occurrence of vibration and noise of the robot.

  In the present embodiment, the second inclined portion 331 of the circular spline 33 and the first inclined portion 231 of the fixed plate 23 are respectively formed over the entire circumference of the circular spline 33. The pressing force against the spline 33 is evenly distributed. Therefore, even if the circular spline 33 is deformed (for example, toward the inside) by the pressing force, the circular spline 33 is deformed as a whole, and local deformation (deformation in which the inner surface of the circular spline 33 undulates) occurs. It is suppressed. As a result, it is possible to suppress the occurrence of vibration and noise when the tightening torque of the bolt 35 when fastening the fixed plate 23 is increased as a whole.

  The circular spline 33 is subjected to a force to rotate in the circumferential direction as the wave generator 31 rotates. In the present embodiment, the circular spline 33 has a clockwise force when viewed from the top surface of FIG. Even if it works, the force is regulated by the engagement of the stepped portion 333 of the circular spline 33 and the stepped portion 232 of the fixed plate 23. When a counterclockwise force is applied, the force is converted into a force that pushes the fixed plate 23 toward the motor 21 by surface contact between the inclined surface 332 of the circular spline 33 and the inclined surface 232 of the fixed plate 23. Is done. However, in the present embodiment, since the fixing plate 23 is fixed to the housing 24 with the bolts 35, this force (force to push the fixing plate 23 toward the motor 21) is regulated by the fixing plate 23. Become. Therefore, according to the present embodiment, the circular spline 33 can sufficiently transmit torque for driving the joints of the robot without fixing with bolts.

  Further, in this embodiment, since the bolt for fixing the circular spline 33 to the housing 24 is not necessary, the wave gear reducer 22 can be reduced in size, and the number of assembling steps can be reduced. . Therefore, the manufacturing cost of the wave gear reducer 22 can be significantly reduced.

  Moreover, in this embodiment, since the circular spline 33 and the fixed plate 23 were formed with the same material, these can be made into the same thermal expansion coefficient. Therefore, even if the motor 21 generates heat and the fixed plate 23 thermally expands, the circular spline 33 can follow the thermal expansion. Therefore, it is possible to further reduce noise and vibration.

D. Variations:
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to such Embodiment, A various structure can be taken in the range which does not deviate from the meaning. For example, the following modifications are possible.

  In the above embodiment, the number of the second inclined portions 231 of the fixed plate 23 and the number of the first inclined portions 331 of the circular spline 33 are each one. On the other hand, as shown in FIGS. 4 and 5, the fixed plate 23b and the circular spline 33b may be provided with a plurality of inclined portions 231b and 331b, respectively. Note that the smaller the number of inclined portions, the higher the processing accuracy of the fixed plate 23 and the circular spline 33 can be increased, so that the assembly error can be reduced.

  The dimension of the outer diameter of the circular spline 33 and the height of the step portion in the above embodiment are not limited to the values described above, and can be arbitrarily set. For example, the heights of the stepped portions 333 and 233 can be appropriately set according to the rated torque of the circular spline 33.

  In the above embodiment, the wave gear reducer 22 is used for a robot, but may be used for industrial equipment other than robots, production facilities, vehicles, transportation equipment, and the like.

  In the above embodiment, the circular spline 33 and the fixed plate 23 are formed of the same material, but may be formed of different materials.

  In the above embodiment, the fixing plate 23 is directly fixed to the housing 24 by the bolts 35. On the other hand, for example, the circular spline 33 and the fixed plate 23 have substantially the same diameter, and through holes are provided in the outer peripheral portions of the circular spline 33 and the fixed plate 23. Then, the fixing plate 23 may be fixed to the casing 24 via the circular spline 33 by fastening the fixing plate 23 to the casing 24 through bolts through the through holes.

DESCRIPTION OF SYMBOLS 21 ... Motor 21a ... Output shaft 22 ... Wave gear reducer 23 ... Fixed plate 24 ... Case 24a, 24b ... Horizontal surface 25 ... Cylindrical part 25a ... First step part 25b ... Second step part 25c ... Third step part 31 ... Wave generator 32 ... Flex spline 32a ... External tooth 32b ... Upper surface part 32c ... Boss part 33 ... Circular spline 33a ... Internal tooth 35, 38 ... Bolt 35b ... Bolt fixing hole 37 ... Mounting member 231 ... First inclined part 331 ... First 2 Inclined portion 232, 332 ... Inclined surface 233, 333 ... Stepped portion

Claims (3)

A wave gear reducer attached to a robot housing,
A wave generator having an elliptical cam;
A cup-shaped flexspline that has outer teeth formed on the outer periphery and is arranged outside the wave generator;
A ring-shaped circular spline in which more inner teeth than the outer teeth are formed on the inner periphery, and the flexspline is disposed on the inner periphery,
The circular spline is sandwiched between a fixing plate and the casing, and is fixed to the casing by fastening the fixing plate to the casing with a bolt.
The contact portion of the circular spline with respect to the fixed plate and the contact portion of the fixed plate with respect to the circular spline are respectively inclined surfaces inclined in the circumferential direction and step portions provided at end portions of the inclined surfaces. Is formed over the entire circumference of the circular spline,
The inclined surface of the inclined portion of the circular spline and the inclined surface of the inclined portion of the fixed plate are in surface contact, and the step portion of the inclined portion of the circular spline and the step portion of the inclined portion of the fixed plate are engaged. ,
Wave gear reducer. The wave gear reducer according to claim 1,
The wave gear reducer, wherein the circular spline and the fixed plate are each provided with one inclined portion. The wave gear reducer according to claim 1 or 2,
The circular spline and the fixed plate are wave gear reducers formed of the same material.

Images