JP2011020214A - Mounting structure of rotary driving mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of a rotary driving mechanism capable of easily adjusting the backlash between gears without depending on the experiences of a worker. <P>SOLUTION: The backlash when engaging a first gear 21 of a driven rotating mechanism 20 with a second gear 41 of a reduction gear 40 as one kind of a rotating drive mechanism is adjusted. A plurality of bolt through-holes 80 are formed in a reduction gear mounting part 30 of a frame 50 at an equal spacing so as to be located on the same circumference. A plurality of screw holes 70 located on the same circumference offset to the center of rotation of the second gear 41 are formed in a casing 43 of the reduction gear 40 so as to be communicated with the bolt through-holes 80. The mounting position of the casing 43 is changed so that the screw holes 70 are communicated with the bolt through-holes 80. In this condition, a state in which the backlash between the first gear 21 and the second gear 41 becomes the desired value is selected, bolts 75 are screwed in the screw holes 70 through the bolt through-holes 80, and the casing 43 is mounted thereon. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mounting structure for a rotary drive mechanism used for a joint shaft of an industrial robot such as an arc welding robot.

  As an arc welding robot, which is a kind of industrial robot, one having a six-axis joint structure is widely used. For driving each axis (each joint), a direct drive using the rotation of the motor directly, and a motor The transmission drive that uses the rotation of the motor via a belt or a speed reducer is properly used.

  Here, as a form of transmission drive, a gear (first gear) is attached to a driven rotation shaft of a driven rotation mechanism that rotates a predetermined arm, and a gear (second gear) is attached to the output-side rotation shaft of the speed reducer. ) Is meshed with the first gear, and the rotation of the motor is transmitted using a belt to a pulley attached to the input side rotation shaft of the speed reducer (see, for example, Patent Document 1). Also, a gear (first gear) is attached to the driven rotation shaft of a driven rotation mechanism that rotates a predetermined arm, and the gear (second gear) attached to the output-side rotation shaft of the speed reducer meshes with the first gear. A configuration is known in which a gear (fourth gear) attached to a drive shaft of a motor is engaged with a gear (third gear) attached to an input-side rotation shaft of a speed reducer (for example, Patent Documents). 2). In any of these configurations, the rotation of the drive shaft of the motor is transmitted to the first gear of the driven rotation mechanism via the speed reducer, and the driven rotation shaft rotates.

  In such transmission drive in which a plurality of gears are engaged, it is necessary to appropriately adjust the backlash (backlash) between the gears. Generally, the position of the driven rotating shaft is determined in advance, and the backlash between the gears is adjusted by adjusting the position of the speed reducer.

  As a method for this, Patent Document 2 discloses that a base shaft is provided at the center of one surface of a disc member having an arc-shaped slit formed at a predetermined position, and the output side rotation shaft of the speed reducer is located at an eccentric position on the other surface. A method using a flange having a structure provided with an eccentric shaft is disclosed. More specifically, the base shaft is rotatably inserted into a hole formed in a predetermined position of the frame of the arm, and a plurality of screw holes formed in the frame are communicated with the slit while adjusting the position of the eccentric shaft. Bolts are screwed through the slits to fix the disk member to the frame. Thereby, the backlash between the first gear of the driven rotation mechanism and the second gear attached to the eccentric shaft can be adjusted.

JP-A-5-169389 JP-A-6-297377

  However, in the backlash adjustment method disclosed in Patent Document 2, the position adjustment of the eccentric shaft serving as the output side rotation shaft of the speed reducer is performed depending on the experience and intuition of the operator. The mounting position tends to be different. In this case, the speed reducer is not always attached to an appropriate position, and the turning performance of the arm may vary for each arc welding robot. Furthermore, even if the disk member is once positioned with respect to the frame, the disk member may be displaced with respect to the frame during the bolting operation for fixing the disk member to the frame.

  The present invention has been made in view of such circumstances, and provides a mounting structure for a rotary drive mechanism that can adjust the backlash between gears under certain conditions without depending on the operator's experience or the like. Objective.

  The rotation drive mechanism mounting structure according to the present invention is a mounting structure for adjusting the position of a rotation drive mechanism for driving a driven rotation mechanism provided on a predetermined arm of an industrial robot to a frame constituting the arm. The driven rotation mechanism includes a driven rotation shaft that is rotatably provided on the frame, and a first gear that is pivotally supported by the driven rotation shaft, and the rotation drive mechanism includes the first rotation shaft. A second gear that meshes with the gear and rotates the first gear, a drive rotary shaft that pivotally supports the second gear, and a casing that rotatably holds the drive rotary shaft and is attached to the frame. The frame includes a plurality of bolt insertion holes formed at a predetermined interval so as to be positioned on the same circumference, and the casing is configured to communicate with the plurality of bolt insertion holes. Times A plurality of screw holes formed at predetermined intervals so as to be located on the same circumference centered on a point that is a predetermined distance away from the axis center of the shaft, the plurality of screw holes and the plurality of bolt insertion holes; The casing is attached to the frame using bolts so as to communicate with each other.

  According to such a configuration, the mounting position of the casing with respect to the frame is sequentially changed so that the plurality of screw holes and the plurality of bolt insertion holes communicate with each other, and at that time, the first gear and the second gear The casing is positioned by selecting a state in which the backlash between the gears is a desired value or a value close to the desired value, and a predetermined bolt is screwed into the screw hole through the bolt insertion hole. Is attached to the frame. At this time, since the casing mounting position of the rotational drive mechanism is limited by the number and positions of screw holes, the mounting position does not vary depending on the experience and intuition of the operator who adjusts the position of the rotational drive mechanism. The backlash between the first gear of the driven rotation mechanism and the second gear of the rotation drive mechanism can be reliably adjusted to a predetermined value state or a state close to the predetermined value. Further, since the mounting position of the casing with respect to the frame is limited by the screw hole and the bolt insertion hole, the labor for adjusting the backlash can be greatly reduced.

  In the rotational drive mechanism mounting structure according to the present invention, the rotational drive mechanism is preferably a speed reducer, and in this case, the output side rotational shaft of the speed reducer is the drive rotational shaft. The second gear that is pivotally supported on the drive rotation shaft and the casing that rotatably holds the drive rotation shaft are components of the speed reducer. A wave gear device is preferably used as the speed reducer.

  In such a configuration, a drive source such as a motor is required to operate the speed reducer. After the speed reducer is positioned as described above with respect to the driven rotation mechanism and attached to the frame, the motor and The transmission of rotation with the speed reducer can be easily adjusted using, for example, a belt, so that the operation of the speed reducer itself can be easily adjusted. Further, since the wave gear device has a compact structure, the space can be saved by using the wave gear device.

  In the mounting structure of the rotary drive mechanism according to the present invention, the plurality of screw holes are formed at equal intervals on the circumference in the casing, and the bolt insertion holes are equally spaced on the circumference in the frame. The number of the plurality of screw holes is a natural number times the number of the plurality of bolt insertion holes, or the number of the plurality of bolt insertion holes is a natural number of the number of the plurality of screw holes. It is preferable that it is several times.

  In a configuration in which the number of screw holes is a natural number multiple of the number of bolt insertion holes, the number of bolt mounting holes to be formed in the frame is kept small, while the number of casing mounting position options is as many as the number of screw holes. can do. Conversely, if the number of bolt insertion holes is a natural number multiple of the number of screw holes, the number of bolt insertion holes can be selected as the casing mounting position option while keeping the number of screw holes formed in the casing small. Can only be ensured.

  The rotation drive mechanism mounting structure according to the present invention is preferably applied to an arc welding robot. That is, the industrial robot is an arc welding robot, and the predetermined arm is an arm that swingably supports a wrist member that holds a welding torch, and the wrist member is driven by the driven rotation mechanism. It is preferable that the wrist member is pivotally supported on the driven rotation shaft so as to be swingable.

  According to such a configuration, in the arc welding robot, the swinging performance of the welding torch can be easily set to a good state.

  According to the present invention, when the rotational drive mechanism is mounted on the frame constituting the arm of the industrial robot by adjusting the position, the mounting position does not vary depending on the operator, and thus the driven rotation is performed. The rocking performance of the mechanism can be set in a good state. In addition, it is possible to suppress variation in the swing performance of the driven rotation mechanism for each industrial robot. Further, the backlash between the gear of the driven rotation mechanism and the gear of the rotation drive mechanism can be reliably adjusted to a predetermined value state or a state close to the predetermined value, and the labor of the adjustment work can be greatly reduced. .

It is a side view which shows schematic structure of the arc welding robot which concerns on this invention. (A) is a schematic sectional drawing which shows the drive mechanism around the wrist rocking | fluctuation axis | shaft J5 which concerns on this invention, (b) is a side view of the drive mechanism seen from the arrow A described to (a). It is a schematic diagram which shows the example of arrangement | positioning of the screw hole formed in the casing of the reduction gear which concerns on this invention. (A) is a schematic diagram which shows the example of arrangement | positioning of the bolt insertion hole formed in the reduction gear attachment part which concerns on this invention, (b) is the screw hole shown in FIG. 3, and the bolt insertion hole shown to (a). It is a schematic diagram which shows an example of the state made to communicate. It is a 1st schematic diagram which shows the form of the change of the position of the 2nd gear with respect to the 1st gear at the time of changing the position of the screw hole connected with respect to each bolt insertion hole which concerns on this invention. It is a 2nd schematic diagram which shows the form of the change of the position of the 2nd gear with respect to the 1st gear at the time of changing the position of the screw hole connected with respect to each bolt insertion hole which concerns on this invention. It is a 3rd schematic diagram which shows the form of the change of the position of the 2nd gear with respect to the 1st gear at the time of changing the position of the screw hole connected with respect to each bolt insertion hole which concerns on this invention. It is a 4th schematic diagram which shows the form of the change of the position of the 2nd gear with respect to the 1st gear at the time of changing the position of the screw hole connected with respect to each bolt insertion hole which concerns on this invention. It is a schematic diagram which shows another embodiment of the screw hole formed in the casing of the reduction gear which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a configuration in which the mounting structure of the rotary drive mechanism according to the present invention is applied to the wrist swing shaft of an arc welding robot which is one of industrial robots will be described. In addition, the positional relationship of each component may be described as being deformed and extremely described.

<Schematic structure of arc welding robot>
FIG. 1 is a side view showing a schematic configuration of the arc welding robot. This arc welding robot includes a base 11 fixed on a floor surface and an arm 10 provided on the base 11. The arm 10 includes a base 12, a first arm 13, a second arm 14, and a wrist member 15. The base 12 is pivotably provided on the base 11 so as to function as the pivot axis J1. A first arm 13 is vertically provided on the upper surface of the base 12, and the first arm 13 is swingable so as to function as the front / rear swing shaft J <b> 2.

  The first arm 13 pivotally supports the second arm 14 on the free end side so as to function as a vertical swing axis J3. The second arm 14 is rotatable so as to function as an arm rotation axis J4, and a wrist member 15 is provided on the free end side thereof. The wrist member 15 is swingable and rotatable so as to function as a wrist swing axis J5 and a wrist rotation axis J6.

  A welding torch 17 is disposed on the wrist member 15 via a torch bracket 18. The torch bracket 18 supports a welding torch 17 by a wrist member 15 driven by a wrist rotation axis J6. The welding torch 17 communicates from the front end surface to the rear end surface, and has a consumable electrode type structure in which the welding wire 16 supplied to the rear end surface is inserted into the welding torch 17 and sent out from the front end surface. . The axial direction of the welding torch 17 and the length direction of the welding wire 16 are substantially parallel. The delivery direction of the welding wire 16 is set along the axis of the wrist rotation axis J6 (or so as to intersect the axis at a constant angle).

  In the arc welding robot configured as described above, a plurality of degrees of freedom are provided by the axes J1 to J6, whereby the tip of the welding wire 16 is placed at an arbitrary position in the three-dimensional spatial coordinates (X, Y, Z). Can be moved.

<Structure around wrist swing axis J5>
2A is a schematic cross-sectional view showing the drive mechanism around the wrist swing axis J5, and FIG. 2B is a schematic side view of the drive mechanism as viewed from the arrow A in FIG. 2A. Show. The arrow B shown in FIG. 2 (a) indicates the direction of the arrow in FIGS. 3, 4 (a), and 4 (b) described later. The second arm 14 provided with a drive mechanism around the wrist swing axis J5 is provided with a drive mechanism for the wrist rotation axis J6 so as not to interfere with the drive mechanism around the wrist swing axis J5. However, illustration of this is omitted (the same applies to FIGS. 4 to 8).

  The frame 50 constituting the second arm 14 which is one of the arms of the arc welding robot has a structure including a cavity 51 extending in the longitudinal direction of the second arm 14 therein. The frame 50 is provided with a driven rotation mechanism 20, a speed reducer 40 as a rotational drive mechanism that directly drives the driven rotation mechanism 20, and a motor 60 for operating the speed reducer 40. Yes. In the drive mechanism around the wrist swing axis J5, the rotation of the drive shaft of the motor 60 is input to the speed reducer 40, and the driven rotation mechanism 20 is driven by the rotational output decelerated by the speed reducer 40.

(Driven rotation mechanism)
The driven rotation mechanism 20 is disposed near the tip of the second arm 14. The driven rotation mechanism 20 includes a driven rotation shaft 22 that is rotatably attached to the frame 50, and a first gear 21 that is pivotally supported on the driven rotation shaft 22. One end of the driven rotary shaft 22 is fixed to the wrist member 15, and the wrist member 15 is swung by the rotation of the driven rotary shaft 22. The driven rotary shaft 22 is held by a holding member 23 having a bearing or the like, and is rotatable about a central axis Q ₁ (synonymous with the wrist swing axis J5). Note that a spur gear is preferably used as the first gear 21, and in this embodiment, a spur gear is used as shown in FIG.

[Reduction gear (rotary drive mechanism)]
A reduction gear 40 is disposed on the frame 50 so as to be aligned with the driven rotation mechanism 20 along the longitudinal direction of the second arm 14. The speed reducer 40 includes a second gear 41 that meshes with the first gear 21, a drive rotary shaft 45 that pivotally supports the second gear 41, and a casing 43 that rotatably holds the drive rotary shaft 45. . When the first gear 21 is a spur gear, a spur gear is also used as the second gear 41 (see FIG. 2B). The drive rotation shaft 45 is an output-side rotation shaft in the speed reducer 40, and the first gear 21 meshed with the second gear 41 rotates as the second gear 41 attached to the drive rotation shaft 45 rotates. The driven rotary shaft 22 can be rotated.

As an input side component for operating the speed reducer 40, the speed reducer 40 includes a pulley 44 and a rotating shaft 42 that pivotally supports the pulley 44, and the rotation of the rotating shaft 42 is driven by a conversion unit 46. Conversion into rotation of the rotation shaft 45 is performed. A rotary shaft 42 and the driving rotary shaft 45, so as to be rotatable on a common center axis Q ₂ around, are arranged coaxially.

  As the speed reducer 40, a wave gear device is preferably used. Since the wave gear device has a large reduction ratio, is small and light, has a large torque capacity, and has a small number of components, the second arm 14 can be made lighter or thinner. . In addition, since the wave gear device has a large number of simultaneously meshing teeth, the influence of the tooth pitch error and the cumulative pitch error on the rotation accuracy is averaged, so that excellent position accuracy and rotation accuracy can be obtained. Has characteristics.

  The casing 43 is attached to the reduction gear attachment 30 that is a part of the frame 50. The speed reducer mounting portion 30 indicates a mounting area (a position recessed by one step from the side surface in FIG. 2) on the frame 50. The principle of mounting the casing 43 to the speed reducer mounting portion 30 will be described later with reference to FIGS. Will be described in detail, and an outline thereof will be described here. As shown in FIG. 2A, the casing 43 is provided with screw holes 70 (generally referring to screw holes 70a to 70h described later) in a plurality of locations, and the speed reducer mounting portion 30 has screw holes 70. Bolt insertion holes 80 (generically referring to bolt insertion holes 80a to 80h described later) are formed at positions where they can communicate with each other. The casing 43 is attached to the reduction gear attachment 30 by screwing the bolt 75 into the screw hole 70 through the bolt insertion hole 80.

〔motor〕
A motor 60 is disposed beside the speed reducer 40 along the longitudinal direction of the second arm 14. A main body portion of the motor 60 is attached to the frame 50, a drive shaft 62 of the motor 60 projects into the cavity 51, and a pulley 61 that is pivotally supported by the drive shaft 62 is located in the cavity 51. Between the pulley 61 of the motor 60 and the pulley 44 of the speed reducer 40, the belt 63 has spans in a state of hanging the constant tension, the central axis Q ₃ around the rotation of the drive shaft 62 of the motor 60 is The rotation speed of the rotary shaft 42 that is transmitted to the pulley 44 of the speed reducer 40 and pivotally supports the pulley 44 is decelerated by the conversion unit 46, and the drive rotary shaft 45 rotates to rotate the second gear 41. As a result, the first gear 21 meshing with the second gear 41 rotates, the driven rotation shaft 22 that pivotally supports the first gear 21 rotates, and the wrist member 15 swings.

[Adjustment method of backlash between first gear and second gear-Position adjustment and attachment method of casing with respect to reduction gear attachment part]
A method of adjusting the backlash between the first gear 21 and the second gear 41, that is, a position adjustment and mounting method of the casing 43 with respect to the speed reducer mounting portion 30 will be described with reference to FIGS. FIG. 3 is a schematic view showing the arrangement of screw holes formed in the casing, and is a view seen from an arrow B shown in FIG. Fig.4 (a) is a schematic diagram which shows arrangement | positioning of the bolt penetration hole formed in the reduction gear attachment part, and is the figure seen from the arrow B shown by Fig.2 (a). FIG. 4B is a schematic diagram illustrating an example of a state in which the screw hole illustrated in FIG. 3 and the bolt insertion hole illustrated in FIG. FIG. 5 is a first schematic diagram illustrating a form of change in the position of the second gear with respect to the first gear when the position of the screw hole communicating with each bolt insertion hole is changed. FIG. 7 is a second schematic diagram, FIG. 7 is a third schematic diagram, and FIG. 8 is a fourth schematic diagram.

In FIGS. 3-8, shows the position of the center axis to Q ₁ driven rotor 22 as viewed from the direction of arrow B shown in FIGS. 2 (a) in the rotation center q _1, the central axis of the drive-rotation shaft 45 It indicates the position Q ₂ 'in the center of rotation _{q 2.} Since the rotation center q ₁ is the rotation center of the first gear 21 and the rotation center q ₂ is the rotation center of the second gear 41, in the following description, “rotation center q ₁ of the first gear 21”, The rotation center q ₂ of the second gear 41 is referred to, and the first gear 21 and the second gear 41 are schematically illustrated in FIGS. 3 to 8 instead of the driven rotation shaft 22 and the drive rotation shaft 45. And In FIGS. 3 to 8, the detailed drawing of the teeth (outer irregularities (see FIG. 2B) that function as gears) is omitted for the first gear 21 and the second gear 41, and the first gear 21 is an arc. Assume that the region between M ₁ and M ₂ and the region between the arcs N ₁ and N ₂ for the second gear 41 are tooth (unevenness) regions, respectively.

As shown in FIG. 3, in the casing 43, a radius r centered on a point P ₁ (hereinafter referred to as “center point P ₁ ”) that is separated from the rotation center q ₂ of the second gear 41 by a distance S in the radial direction. at equal intervals in eight positions on the circumference _{C 1} of the screw holes 70a, 70b, 70c, 70d, 70e, 70f, 70g, 70h ( in view indicating the position, and to draw by black dots) are formed . Here, as the rotation center q ₂ of the second gear 41 is located at the screw hole 70e side on a line connecting the screw holes 70a and the screw holes 70e, it defines the position of the center point P _1.

  The value of the distance S is an adjustable length of the backlash between the first gear 21 and the second gear 41. As will be described later, the backlash can be adjusted with a predetermined value within the range of twice the distance S. 3, 4 (a), and FIGS. 5 to 8, in order to clearly show the change in the meshing region of the first gear 21 and the second gear 41 depending on the mounting position of the casing 43, the value of the distance S is increased. Due to this, in FIGS. 3 to 8, the regions of the teeth (unevenness) of the first gear 21 and the second gear 41 are wide.

As shown in FIG. 4A, in the speed reducer mounting portion 30, a point P ₂ (hereinafter referred to as “center point P ₂ ”) that is separated from the rotation center q ₁ of the first gear 21 by a certain distance R is provided. Bolt insertion holes 80 a, 80 b, 80 c, 80 d, 80 e, 80 f, 80 g, and 80 h are formed at equal intervals at eight locations on the circumference C ₂ having a radius r at the center. The distance R is unchanged and is determined in consideration of the diameters and tooth depths of the first gear 21 and the second gear 41.

The direction connecting the rotation center _{q 1} and the center point _{P 2} of the circumference _{C 2} of the first gear 21 and the X direction, the X direction and the center axis _{Q 1} (center axis _{Q 1} is, through the rotation center _{q 1,} The direction perpendicular to the plane of the drawing is defined as the Y direction. Furthermore, the center point _{P 2} of the circumference _{C 2} as the origin, the X-Y coordinate system indicating the position of the rotation center _{q 2} of the second gear 41 defines as shown in FIG. 4 (a) (FIG. 5 The same applies in FIG. 8).

As shown in FIG. 4B, the same number of screw holes 70 and bolt insertion holes 80 are formed at the same intervals on the circumferences C ₁ and C _{2 of} radius r. -The casing 43 is mounted on the reduction gear mounting portion so that the combination of the screw holes 70 is, for example, [80a-70a], [80b-70b], ..., [80g-70g], [80h-70h]. 30 can be attached using a bolt 75 (see FIG. 2A).

As mentioned above, the distance between the center point P ₂ of the rotation center q ₁ and set to the reducer mounting portion 30 a circumferential C ₂ of the first gear 21 is constant at R, as described above, q ₂ and since the distance _{P 1} is S, in a state shown in FIG. 4 (b), according to X-Y coordinate system defined in FIG. 4 (a), the center of rotation _{q 2} of the second gear 41 coordinates When (X, Y) is determined, the coordinates are (X, Y) = (S, 0). That is, the rotation center _{q 1} of the first gear 21 distance between the rotation center _{q 2} of the second gear 41 becomes "R + S".

In the drive mechanism around the wrist swing axis J5, the rotation center q of the second gear 41 is changed by changing the combination of [bolt insertion hole 80-screw hole 70] when the speed reducer 40 is attached to the speed reducer mounting portion 30. The coordinates of ₂ change. The backlash between the first gear 21 and the second gear 41 is adjusted using the change in the distance between the rotation center q ₁ of the first gear 21 and the rotation center q _{2 of} the second gear 41. This will be described in more detail with reference to FIGS.

FIG. 5 (a) shows the same state as FIG. 4 (b). The rotation center _{q 1} of the first gear 21 X-direction distance between the rotation center _{q 2} of the second gear 41 is a "R + S". FIG. 5A shows a state in which the second gear 41 is arranged farthest from the first gear 21.

5B, the casing 43 is rotated 45 degrees counterclockwise (counterclockwise) from the state shown in FIG. 5A, and the combination of [bolt insertion hole 80-screw hole 70] is [80a. −70h], [80b-70a],..., [80g-70f], [80h-70g], and shows the state where the casing 43 is attached to the reduction gear attachment 30. The coordinates (X, Y) of the rotation center q ₂ of 41 are (S / 2 ^1/2 , S / 2 ^1/2 ). In the state shown in FIG. 5 (b), the distance in the X direction between the rotation center _{q 2} of the center of rotation _{q 1} and the second gear 41 of the first gear 21 becomes ^{"R + S / 2 1/2"} . That is, the state shown in FIG. 5B is compared with the state shown in FIG. 5A by moving the second gear 41 to the first gear 21 by a distance “S− (S / 2 ^1/2 )”. The state in which the backlash between the first gear 21 and the second gear 41 is adjusted by approaching in the X direction is shown.

Here, in the state shown in FIG. 5B, the second gear 41 is displaced by “S / 2 ^1/2 ” in the Y direction. It is better if it is in such a state, that is, a state that is displaced only in the X direction without originally shifting in the Y direction, but even if it is shifted in the Y direction (for example, the vertical direction), it is also displaced in the X direction, Even if it is displaced in the X and Y directions, there is no adverse effect on the meshing state of the first gear 21 and the second gear 41. This is because when the distance between the rotation center q ₂ of the center of rotation q ₁ and the second gear 41 of the first gear 21 is constant, the second gear 41 is disposed in which direction the radial direction of the first gear 21 Even so, the meshing state of the first gear 21 and the second gear 41 is substantially the same, so the state shown in FIG. 5B is the rotation center q ₁ of the first gear 21 and the second gear. The distance from the rotation center q _{2 of} 41 to “R + S” is “[(R + S / 2 ^1/2 ) ² + (S / 2 ^1/2 ) ² ] ^1/2 ”. As described above, this is because the backlash between the first gear 21 and the second gear 41 is adjusted.

When the casing 43 is attached to the speed reducer mounting portion 30, the second gear 41 is displaced in the + Y direction as shown in FIGS. 5 and 6, but is displaced in the -Y direction as shown in FIGS. tried, the absolute value of the displacement amount is uniquely determined in accordance with the X-direction coordinate of the rotation center q ₂ of the second gear 41. Therefore, in the adjustment of the backlash between the first gear 21 and second gear 41, for the adjustment and the rotation center q ₁ of the first gear 21 of the actual distance between the rotation center q ₂ of the second gear 41 without the parameter can be the X-direction distance between the rotation center q ₂ of the center of rotation q ₁ and the second gear 41 of the first gear 21 and adjusted.

6A, the casing 43 is rotated 90 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 5B). The casing 43 is decelerated so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70g], [80b-70h],..., [80g-70e], [80h-70f]. shows a state mounted to the machine mounting portion 30, the rotation center _{q 2} of the coordinates of the second gear 41 (X, Y) becomes (0, S). In the state shown in FIG. 6 (a), the rotation center _{q 1} of the first gear 21 X-direction distance between the rotation center _{q 2} of the second gear 41 becomes "R". That is, the state shown in FIG. 6A is compared with the state shown in FIG. 5A by bringing the second gear 41 closer to the first gear 21 by the distance “S” in the X direction. The state in which the backlash between the gear 21 and the second gear 41 is adjusted is shown.

Incidentally, the state shown in FIG. 6 (a), the distance between the rotation center _{q 2} of the center of rotation _{q 1} and the second gear 41 of the first gear 21 ^{"(R 2 + S 2)} 1/2" and made as In addition, the backlash between the first gear 21 and the second gear 41 is adjusted.

6B, the casing 43 is rotated 135 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 6A). The casing 43 is attached to the reduction gear so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70f], [80b-70g], [80g-70d], [80h-70e]. The state attached to the part 30 is shown, and the coordinates (X, Y) of the rotation center q ₂ of the second gear 41 are (−S / 2 ^1/2 , S / 2 ^1/2 ). In the state shown in FIG. 6 (b), the rotation center _{q 1} of the first gear 21 X-direction distance between the rotation center _{q 2} of the second gear 41 becomes ^{"R- (S / 2 1/2)} " . That is, the state shown in FIG. 6B is compared with the state shown in FIG. 5A by moving the second gear 41 to the first gear 21 by a distance “S + (S / 2 ^1/2 )”. A state in which the backlash between the first gear 21 and the second gear 41 is adjusted by approaching in the direction is shown.

Incidentally, the state shown in FIG. 6 (b), the distance between the rotation center _{q 2} of the center of rotation _{q 1} and the second gear 41 of the first gear 21 is ^{"[(R-S / 2} 1/2) 2 + (S / 2 ^1/2 ) ² ] ^1/2 ″ is nothing but an adjustment of the backlash between the first gear 21 and the second gear 41.

7A, the casing 43 is rotated 180 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 6B). The casing 43 is attached to the speed reducer so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70e], [80b-70f], [80g-70c], [80h-70d]. shows a state attached to the part 30, the rotation center _{q 2} of the coordinates of the second gear 41 (X, Y) becomes (-S, 0). In the state shown in FIG. 7 (a), the rotation center _{q 1} of the first gear 21 X-direction distance (Y-coordinate of the center of rotation _{q 2} of the second gear 41 and the rotation center _{q 2} of the second gear 41 is 0 (Equal to the actual distance because it is (zero)) becomes “RS”. That is, the state shown in FIG. 7A is compared with the state shown in FIG. 5A by bringing the second gear 41 closer to the first gear 21 by the distance “2S” in the X direction. The state in which the backlash between the gear 21 and the second gear 41 is adjusted is shown.

7B, the casing 43 is rotated 225 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 7A). The casing 43 is attached to the speed reducer so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70d], [80b-70e], [80g-70b], [80h-70c]. The state attached to the part 30 is shown, and the coordinates (X, Y) of the rotation center q ₂ of the second gear 41 are (−S / 2 ^1/2 , −S / 2 ^1/2 ). In the state shown in FIG. 7 (b), the distance in the X direction between the rotation center _{q 2} of the center of rotation _{q 1} and the second gear 41 of the first gear 21 becomes ^{"R + S 1/2".} That is, in the state shown in FIG. 7B, the second gear 41 is moved closer to the first gear 21 in the X direction by the distance “S + S / 2 ^1/2 ” in contrast to the state shown in FIG. Thus, the backlash between the first gear 21 and the second gear 41 is adjusted.

  The meshing state between the first gear 21 and the second gear 41 shown in FIG. 7B is equivalent to the meshing state between the first gear 21 and the second gear 41 shown in FIG. .

8A, the casing 43 is rotated 270 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 7B). The casing 43 is attached to the speed reducer so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70c], [80b-70d], [80g-70a], [80h-70b]. It shows a state attached to the part 30, the rotation center _{q 2} of the coordinates of the second gear 41 (X, Y) becomes (0, -S). In the state shown in FIG. 8 (a), the rotation center _{q 1} of the first gear 21 X-direction distance between the rotation center _{q 2} of the second gear 41 becomes "R". That is, the state shown in FIG. 8A is compared with the state shown in FIG. 5A by bringing the second gear 41 closer to the first gear 21 by the distance “S” in the X direction. The state in which the backlash between the gear 21 and the second gear 41 is adjusted is shown.

  The meshing state of the first gear 21 and the second gear 41 shown in FIG. 8A is equivalent to the meshing state of the first gear 21 and the second gear 41 shown in FIG. .

8B, the casing 43 is rotated 315 ° counterclockwise from the state shown in FIG. 5A (the casing 43 is rotated 45 ° counterclockwise from the state shown in FIG. 8A). The casing 43 is attached to the speed reducer so that the combination of [bolt insertion hole 80-screw hole 70] is [80a-70b], [80b-70c]... [80g-70h], [80h-70a]. The state attached to the part 30 is shown, and the coordinates (X, Y) of the rotation center q ₂ of the second gear 41 are (S / 2 ^1/2 , −S / 2 ^1/2 ). In the state shown in FIG. 8 (b), the rotation center _{q 1} of the first gear 21 X-direction distance between the rotation center _{q 2} of the second gear 41 becomes ^{"R + S / 2 1/2"} . That is, the state shown in FIG. 8B is compared with the state shown in FIG. 5A by moving the second gear 41 to the first gear 21 by the distance “S−S / 2 ^1/2 ” in the X direction. As a result, the backlash between the first gear 21 and the second gear 41 is adjusted.

  The meshing state of the first gear 21 and the second gear 41 shown in FIG. 8B is equivalent to the meshing state of the first gear 21 and the second gear 41 shown in FIG. .

  When the casing 43 is rotated 45 degrees counterclockwise from the state shown in FIG. 8B, the state shown in FIG. 5A is restored.

  As described above, the value that can be taken by the adjustment amount of the backlash when the casing 43 is attached to the reduction gear attachment 30 is not a continuous value but a stepwise value. Therefore, which of the states shown in FIGS. 5 to 8 is determined as the mounting position of the casing 43 with respect to the reduction gear mounting portion 30 and is actually mounted is determined between the first gear 21 and the second gear. The backlash is performed based on a predetermined adjustment amount.

Specifically, the states (mounting positions) shown in FIGS. 5 to 8 are realized by temporarily fixing the casing 43 to the reduction gear mounting portion 30 or the like, and the first gear 21 and the second gear in each state. 41 backlashes are measured. That is, the rotation center q ₂ (drive) of the second gear 41 with respect to the center point P ₂ of the circumference C ₂ connecting the bolt insertion holes 80a to 80h so that the screw hole 70 and the bolt insertion hole 80 are individually communicated. A state (eccentric state) in which the position of the central axis Q ₂ ) of the rotating shaft 45 is shifted is created, and the backlash of the first gear 21 and the second gear 41 at that time is measured. Then, it is determined which position the casing 43 is in and the measured value of the backlash becomes a predetermined adjustment amount or a value close to this adjustment amount, and one position is determined. At the position determined in this way, a predetermined bolt 75 is screwed into the screw hole 70 through the bolt insertion hole 80, and the casing 43 is attached to the reduction gear attachment 30.

  In addition, when the measured value of the backlash before and after rotating the casing 43 by 45 ° is the same in two positions (including the case where it can be regarded as substantially the same due to a slight difference), select any position. However, the driving performance of the second arm 14 is not affected. The tension of the belt 63 may be adjusted after the speed reducer 40 has been positioned.

  According to such a position adjustment and attachment method of the backlash between the first gear 21 and the second gear 41, when the speed reducer 40 is adjusted and attached to the frame 50, the attachment depends on the operator. The position is never different. Thereby, the rocking | fluctuation performance of the wrist member of an arc welding robot is securable. Moreover, it can suppress that dispersion | variation arises in the rocking | fluctuation performance of the wrist member 15 for every arc welding robot. Further, the backlash between the first gear 21 and the second gear 41 can be reliably adjusted to an adjustment amount of a predetermined value or a value close to this adjustment amount, and work effort at that time can be reduced. .

[Another embodiment of the screw hole formed in the casing]
FIG. 9 is a schematic view showing another embodiment of the screw hole formed in the casing of the speed reducer. FIG. 9 is depicted in the same manner as FIG. This casing 43, 16 locations of the screw holes 70a~70p are formed at equal intervals on the circumference _{C 1.} Thus, by increasing the number of screw holes 70 formed on the circumference C _1, the adjustment of the backlash between the first gear 21 and second gear 41, so as to perform more precisely Become.

  Even when 16 screw holes 70a to 70p are formed in the casing 43, the number of bolt insertion holes formed in the speed reducer mounting portion 30 may be 8 as shown in FIG. If the number of screw holes 70 is a natural number multiple of the number of bolt insertion holes 80, all the bolt insertion holes 80 are always in communication with the screw holes 70, and the positions of the mounting positions of the casing 43 to the speed reducer mounting portion 30 are determined. As many options as the number of screw holes 70 can be secured.

  Conversely, although not shown, the number of bolt insertion holes 80 may be a natural number times the number of screw holes 70. In this case, since all of the screw holes 70 formed in the casing 43 can always create a state of communicating with the bolt insertion holes 80, the number of bolt insertion holes 80 assures the choice of the mounting position of the casing 43. can do.

As described above, the embodiment of the present invention has been described as the configuration in which the screw hole 70 of the casing 43 is formed so as to be decentered from the concentric circle of the rotating shaft 42 provided in the casing 43. The form is not limited. For example, the casing 43 of the reducer 40 is provided a screw hole 70 on one circumference C _1, and is provided with the bolt insertion holes 80 on one circumference C ₂ in reduction gear mounting portion 30, a screw hole When many 70 and bolt insertion holes 80 are provided, these may be formed separately on two concentric circles. For example, the casing 43 shown in FIG. 9, a screw hole 70I～70p, arranged on the circumference of a different radius than the circumference _{C 1.} At this time, the central angle _{(70a-P 1 -70i),} (70i-P 1 -70b), ···, (70h-P 1 -70p), the same each angle _(70p-P 1 -70a) Then, the screw holes 70i to 70p are positioned. Then, the speed reducer mounting portion 30 may be further formed with bolt insertion holes 80 corresponding to the screw holes 70i to 70p.

  Further, although the case where the rotation drive mechanism mounting structure according to the present invention is applied to the joint shaft of an arc welding robot has been described, the present invention is not limited to this, and other various industrial robots (spot welding robots, assembly robots). It can be applied to a joint axis of a transfer robot or the like. Moreover, although the form which used the reduction gear as a rotational drive mechanism was demonstrated, you may use a motor directly as a rotational drive mechanism, and the attachment structure of the rotational drive mechanism which concerns on this invention is used for position adjustment and attachment of a motor. You can also

  Further, although spur gears are exemplified as the first gear 21 and the second gear 41, the first gear 21 and the second gear 41 can implement the above-described method for adjusting the backlash of the first gear 21 and the second gear 41. For example, a tapered gear may be used. As the speed reducer 40, an input side rotating shaft (rotating shaft 42) and an output side rotating shaft (drive rotating shaft 45) are shown as having a coaxial structure, but those having parallel axes are used. May be.

14 second arm 20 driven rotation mechanism 21 first gear 22 driven rotation shaft 30 reduction gear mounting portion 40 reduction gear (rotation drive mechanism)
41 Second gear 42 Rotating shaft 43 Casing 44 Pulley 45 Driving rotating shaft 46 Conversion unit 50 Frame 60 Motor 61 Pulley 62 Driving shaft 63 Belt 70, 70a to 70p Screw hole 75 Bolt 80, 80a to 80h Bolt insertion hole

Claims (5)

An attachment structure for attaching a rotational drive mechanism for driving a driven rotational mechanism provided on a predetermined arm of an industrial robot to a frame constituting the arm,
The driven rotation mechanism includes a driven rotation shaft that is rotatably provided on the frame, and a first gear that is pivotally supported on the driven rotation shaft,
The rotary drive mechanism includes a second gear that meshes with the first gear and rotates the first gear, a drive rotary shaft that pivotally supports the second gear, and rotatably holds the drive rotary shaft. A casing attached to the frame,
The frame has a plurality of bolt insertion holes formed at predetermined intervals so as to be located on the same circumference,
The casing is formed at predetermined intervals so as to be positioned on the same circumference centered at a point separated from the axial center of the drive rotation shaft by a predetermined distance so as to be able to communicate with the plurality of bolt insertion holes. Has multiple screw holes,
An attachment structure for a rotary drive mechanism, wherein the casing is attached to the frame using bolts such that the plurality of screw holes and the plurality of bolt insertion holes communicate with each other. The rotational drive mechanism is a speed reducer;
The rotation drive mechanism mounting structure according to claim 1, wherein an output-side rotation shaft of the speed reducer is the drive rotation shaft.   The rotational drive mechanism mounting structure according to claim 2, wherein the speed reducer is a wave gear device. In the casing, the plurality of screw holes are formed at equal intervals on the circumference, and in the frame, the plurality of bolt insertion holes are formed at equal intervals on the circumference,
The number of the plurality of screw holes is a natural number times the number of the plurality of bolt insertion holes, or the number of the plurality of bolt insertion holes is a natural number times the number of the plurality of screw holes. The mounting structure for a rotary drive mechanism according to any one of claims 1 to 3, wherein the mounting structure is provided. The industrial robot is an arc welding robot,
The predetermined arm is an arm that swingably supports a wrist member that holds a welding torch,
The wrist member is pivotally supported on the driven rotation shaft so that the wrist member can swing freely by driving the driven rotation mechanism. 2. A mounting structure of the rotation drive mechanism according to 1.

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