JPH0740112Y2 - Backlash removal mechanism for industrial robots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a backlash removing mechanism for removing backlash in a rotational force transmission system having bevel gears such as joints and arm drives of an industrial robot. It is about.

[Prior Art] Generally, in a rotational force transmission system such as a joint part (a wrist part) or an arm drive part of an industrial robot, when a speed reducer for a robot with extremely small backlash cannot be used as a speed reducer, When a bevel gear is used for the purpose of changing the direction other than the speed reducer, the backlash is a problem. In particular, a general bevel gear has a large backlash, and it is necessary to devise a method for removing the backlash.

Therefore, in the rotation mechanism section including the bevel gear, conventionally,
As a backlash removing mechanism, one shown in FIG. 5 has been proposed.

That is, the rotary shaft 41 has one end connected to a rotary drive means such as a motor (not shown), the other end to which the bevel gear 42 is attached, and the rotary shaft 41 is supported by a bearing 43. The output shaft 44 arranged orthogonal to the rotary shaft 41 is rotatably supported by a bearing 45, and has a bevel gear 46 meshing with the bevel gear 42 attached to one end thereof. The bevel gear 46 is fastened and fixed to the output shaft 44 by a plurality of bolts 48 via a backlash adjusting liner 47.

Therefore, the driving force from the rotation driving means (not shown) is transmitted to the output shaft 44 in the orthogonal direction via the rotating shaft 41, the bevel gear 42 and the bevel gear 46.

In such a mechanism, when removing the backlash between the bevel gears 42, 46, the bevel gear 46 is moved in the up-down direction of FIG.
After adjusting the plate thickness or the number of the liner 47 between the bevel gear 46 and the output shaft 44 so that the bevel gear 46 is at an appropriate position, the bolt 48 is tightened to fix the bevel gear 46.

Generally, the position where the output shaft 44 of the robot is to be arranged is fixed at a predetermined position and cannot be changed.
The output shaft 44 itself cannot be moved in its axial direction (vertical direction in FIG. 5). Therefore, the output shaft 44 and the bevel gear 46
It is necessary to adjust the backlash with the bevel gear 42 by relatively changing the positions of and. Further, at this time, in order to fix the output shaft 44 and the bevel gear 46 in the rotational direction while allowing relative movement in the axial direction, it is conceivable to use a spline, a sliding key, or the like. In addition to being complicated, the rattling that newly occurs due to these mechanisms becomes a problem.

For these reasons, the liner 47 is conventionally used to adjust the backlash as described above.

[Problems to be Solved by the Invention] However, in the above-mentioned backlash removing mechanism of the industrial robot, it takes a considerable amount of time to adjust the plate thickness or the number of the liners 47, and the wear of the bevel gears 42, 46 is increased. Since there is a disadvantage in readjustment (maintenance) associated with the above, improvement has been desired.

Further, the wrist of an industrial robot often has two or more sets of bevel gears, and a mechanism for removing the backlash of any bevel gear is required.

The present invention is intended to solve the above problems,
An object of the present invention is to provide a backlash removing mechanism for an industrial robot which has a simple structure and can be easily adjusted without causing backlash.

[Means for Solving the Problems] In order to achieve the above object, a backlash removing mechanism of an industrial robot according to the present invention includes a reduction gear arranged in a casing of the robot and an output shaft. In a backlash removing mechanism of an industrial robot having two sets of bevel gear mechanisms, rotary shafts which are directly connected to the speed reducer, are connected to a rotation driving means through the speed reducer, and have bevel gears at one ends thereof and are parallel to each other. An output shaft having a bevel gear at one end, a transmission shaft provided between the rotating shaft and the output shaft and extending orthogonal to the axial direction of the rotating shaft, and an umbrella of the rotating shaft supported by the transmitting shaft. A pair of gear members each having two bevel gears meshing with the gear and the bevel gear of the output shaft, wherein the gear member is rotated in the axial direction of the transmission shaft by rotation of a screw screwed to the transmission shaft. Movable to While being provided, the rotary shaft is provided between each bearing case of the rotary shaft and the casing, and a position holding mechanism that can hold the rotary shaft at a predetermined axial position is provided,
The bearing case is internally fitted and screwed in the position holding mechanism so as to be movable in the axial direction, and the position holding mechanism has a detent member for the bearing case, and the movement of the rotary shaft is movable in the axial direction in the speed reducer. It is characterized in that it is performed within a margin range.

[Operation] In the backlash removing mechanism of the industrial robot of the present invention described above, the rotary shaft is moved within the allowance range of axial movement within the reduction gear, and is held at the predetermined axial position by the position holding mechanism. As a result, the position of the bevel gear of the rotating shaft with respect to the bevel gear of the output shaft is adjusted, and the backlash between the bevel gear of the output shaft and the bevel gear of the rotating shaft is adjusted / removed.

Further, in the backlash removing mechanism of the industrial robot of the present invention, the two bevel gears, which mesh with the rotary shaft and the output shaft, are formed as an integral structure so as to prevent rattling, and have the two bevel gears. The gear body is moved in the axial direction of the transmission shaft by the rotation of the screw to remove the backlash between the bevel gear of the output shaft and the bevel gear of the gear body, and for this removal, the bevel gear of the output shaft. The increase in backlash caused by the movement of the bevel gear that meshes with the original position and the backlash of the two bevel gears of the rotating shaft and the output shaft are directly connected to the reducer within the margin of the reducer. The shaft and the bevel gear of the rotary shaft can be moved and removed at the same time.

[Embodiment of the Invention] A backlash removing mechanism of an industrial robot as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a joint portion of a robot to which the mechanism of the present embodiment is applied. (A sectional view taken along the line II of FIG. 2), FIG. 2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a plan view showing the arrangement of the limit switch, and FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3.

First, referring to FIGS. 1 and 2, a joint portion of an industrial robot (a manipulator such as an arc welding robot) to which the apparatus of this embodiment is applied and its drive mechanism will be described. This joint has a bending degree of freedom α around the S1 axis (operating angle range 36
It is a two-axis robot wrist 20 having a twisting degree β about the S2 axis (within 0 °) and an operating angle range of 360 ° or more.

Two drive motors (rotational drive means) 2 and 3 are provided in the casing 1 of the robot arm to rotate and drive these two axes, and each drive motor 2 and 3 has a speed reducer (harmonic). Reduction shafts or cyclone reduction gears) are connected to rotary shafts 6 and 7 via
One end of 7 is directly connected to the speed reducers 4 and 5 by screws. The speed reducers 4 and 5 used here are movable in the axial direction, and the rotary shafts 6 and 7 connected directly to them.
Also, by utilizing the function as a spline (circular spline and flex spline if it is a harmonic reducer) necessary for the mechanism of the reducers 4 and 5, within the allowance range in which the reducers 4 and 5 can move in the axial direction. Therefore, it is possible to move in the axial direction by utilizing the margin.

The rotational force from the drive motors 2 and 3 transmitted to the rotary shafts 6 and 7 is transmitted to the rotary shaft (output shaft) 2 via the bevel gear mechanisms 8 and 9, respectively.
9,30, the rotation of the rotary shaft 29 is transmitted as rotation of the wrist 20 around the S1 axis, while the rotation of the rotary shaft 30 is:
The rotation of the S2 axis of the wrist portion 20 is transmitted through the bevel gear mechanism 39 at a reduced speed.

Further, the bevel gear mechanisms 8 and 9, respectively, bevel gears 8a and 9a formed at the other ends of the rotating shafts 6 and 7, respectively, and the bevel gears 8a and 9a mesh with the bevel gears 8a and 9a, respectively. It is composed of bevel gears 8b and 9b attached by 32.

101 is a transmission shaft 101 that is provided between the output shaft 107 around the meshing S1 axis and the rotary shaft 7 and extends in a direction orthogonal to the axial direction of the rotary shaft 7, and includes a bearing 104 and an end plate 10.
The movement of the bevel gear 8b is restricted by the axis 5 and the bevel gear 8b is rotatable. A gear body 108 including a bevel gear 9b and a rotating shaft 30 externally fitted to the transmission shaft 101 is integrally and rotatably supported by a bolt 106 on the transmission shaft 101 so as to be rotatable in the axial direction.

Further, the bevel gear mechanism 39 includes the bevel gear 8 of the rotary shaft 30 of the gear body 108.
The bevel gear 39a is formed at the end on the b side, and the bevel gear 39b is formed at one end of the output shaft 107 that meshes with the bevel gear 39a.

The gear body 108 is rotatable integrally with the transmission shaft by rotating and tightening a bolt 102 that penetrates the member 110 and is screwed into the transmission shaft 101, and the bolt 10
Both bevel gears 9b and 39a of the gear body 108 are pressed against the bevel gears 9a and 39b of the rotating shaft by the tightening force of 2. A set screw 103 is provided between the member 100 and the gear body 108.

The rotary shafts 6 and 7 have bearings 23, 24;
It is rotatably supported with respect to the casing 1 by being axially supported by 5,26.

The inner rings of bearings 24 and 26 are retaining rings for rotating shafts 6 and 7, respectively.
Although fixed by 27, 28, the outer ring is not regulated in the axial direction (the left-right direction in FIGS. 1 and 2) with respect to the casing 1, and the bearings 24, 26 themselves have the rotating shafts 6, 7 Along with that, it can move in the axial direction.

The bearings 23, 25 are interposed between the inner peripheral surfaces of the bearing cases 33, 34 loosely fitted to the rotary shafts 6, 7 and the outer peripheral surfaces of the rotary shafts 6, 7, respectively. The inner ring of the bearings 23, 25 is restricted by the stepped portions 6a, 7a formed on the outer peripheral surfaces of the rotating shafts 6, 7 in the direction of closing the backlash, while the outer rings of the bearings 23, 25 are the inner circumference of the bearing cases 33, 34. The stepped portions 33a, 34a formed on the surface regulate the backlash in a direction in which the backlash is closed.

Further, the adjustment cases 35 and 36 fixed to the casing 1 are fitted onto the bearing cases 33 and 34, respectively.
The screw parts 35a, 36a formed on the inner peripheral surface of the 36 and the bearing case 3
Threaded portions 33b, 34b formed on the outer peripheral surfaces of 3, 34 are respectively screwed together so that the bearing cases 33, 34 are rotatable and axially movable with respect to the adjustment cases 35, 36, respectively. It is provided.

In addition, the adjustment cases 35 and 36 have bearing case 3
Bearings 23 and 25 and rotating shaft
Set screws 37 and 38 for holding 6 and 7 at predetermined axial positions are screwed.

These bearing cases 33, 34, adjustment cases 35, 36 and set screws 37, 38 constitute a position holding mechanism for the rotary shafts 6, 7, respectively, and each position holding mechanism and bearings 24, 2
6 constitutes a backlash removing mechanism (the operation will be described later) of this embodiment.

In addition, on the rotary shafts 6 and 7 in the casing 1, slide keys 10 and 11 are provided so as to protrude along the axial direction, and male screw members 12 and 13 are externally fitted so as to be slidable in the axial direction. . The male screw members 12 and 13 are engaged with the sliding keys 10 and 11 and
It rotates together with 6, 7 (without relative rotation) and moves only in the axial direction.

In addition, the casing 1 in the outer peripheral portion of the male screw members 12 and 13
Fixed guides 14 and 15 for guiding the male screw members 12 and 13 are attached thereto. Each of the fixed guides 14 and 15 corresponds to a part (rack shape) of a nut that can be screwed into the threads 12a and 13a on the outer circumferences of the male screw members 12 and 13, respectively.
Is guided by being screwed into the fixed guides 14 and 15, respectively, so that it can move along the sliding keys 10 and 11 in the axial direction while rotating integrally with the rotating shafts 6 and 7. Then, as shown in FIGS. 2 to 4, when the male screw members 12 and 13 are moved to predetermined positions, they are actuated by the male screw members 12 and 13 to detect the turning positions of the rotary shafts 6 and 7, respectively. Limit switches 16a, 16b; 17a, 17b are provided. The limit switches 16a, 16b are operated by abutting on the end faces 12b, 12c of the threads 12a of the male screw member 12, respectively.
Similarly, the limit switches 17a and 17b operate by abutting on the respective end faces 13b and 13c of the thread 13a of the male screw member 13, respectively.

Further, in this embodiment, as shown in FIG. 1, rubber stopper members 18 and 19 are provided at positions outside the limit switches 17a and 17b (moving limit position of the male screw member 13 at a predetermined width direction position). A mechanical stopper mechanism for fitting around the S2 axis of the wrist 20 is constructed by being externally fitted to the end of the rotary shaft 7, respectively. The stopper members 18 and 19 contact the axial end faces 13d and 13e of the male screw member 13, respectively, and mechanically restrict the movement of the male screw member 13 and the rotation of the rotary shaft 7 at the movement limit position. Although the above-mentioned stopper member is not provided on the rotary shaft 6 side,
Is a rubber stopper 21,22 attached to the casing 1.
Then, the wrist portion 20 is brought into contact with the wrist portion 20, so that the wrist portion 20 is mechanically regulated.

Since the backlash removing mechanism of the industrial robot as one embodiment of the present invention is configured as described above, the first method is adopted when removing the backlash between the bevel gears 39a and 39b.
By removing the cover of the casing 1 on the side of the bevel gear mechanism 8 and 9 shown in the figure and rotating and loosening the bolt 102, the gear body 108 is transmitted by the tightening force of the bolt 102.
It is removed by moving it in the axial direction of 1 (upward in FIG. 1).

Then, when removing the backlash generated in the bevel gear 9b by the movement of the gear body 108 and the backlash between the bevel gears 8a, 8b or the bevel gears 9a, 9b, in the state where the set screws 37, 38 are loosened. , The bearing case 33, 3 is formed by using a hole for a rotatable jig formed from the outside formed in the bearing case 33, 34.
Loosen the screwed state with 4 and move it in the axial direction (to the left in Figs. 1 and 2).

When the bearing cases 33, 34 move in the axial direction, the bearing cases 33, 34
The rotary shafts 6 and 7 are driven in the same direction via the bearings 23 and 25 whose positions are regulated by the rotary shaft 34 and the rotary shafts 6 and 7. At this time, as the speed reducers 4 and 5, the ones that are movable in the axial direction are used as described above, and the bearings 24 and 26 are provided so as to be movable in the axial direction with respect to the casing 1. 6,7 as a whole, the bearings 23,24; 25,26 and bearing case 3
Moves axially with 3,34.

In this way, the rotary shafts 6 and 7 are moved in the axial direction thereof and arranged at predetermined axial positions where backlash can be removed, and then the set screws 37 and 38 are tightened. As a result, the relative rotation of the bearing cases 33, 34 with respect to the adjustment cases 35, 36, that is, the movement of the rotary shafts 6, 7 is restricted, and
6,7 are held in place and the bevel gears 8b, 9 on the rotating shafts 29,30
The positions of the bevel gears 8a and 9a of the rotating shafts 6 and 7 with respect to b are adjusted, respectively, and the backlash between the bevel gears 8a and 8b or 9a and 9b is adjusted and removed.

When the rotary shafts 6 and 7 are driven to rotate by the drive motors 2 and 3, the male screw members 12 and 13 move along the axial direction while rotating integrally with the rotary shafts 6 and 7, respectively. To do.
Then, when the threads 12a and 13a of the male screw members 12 and 13 respectively rotate a predetermined number of times and move to a predetermined axial position, for the male screw member 12, each end surface 1 of the screw thread 12a.
2b and 12c come into contact with the limit switches 16a and 16b, respectively, and the limit switches 16a and 16b are actuated to detect the operation limit position of the rotary shaft 6. Similarly, the male screw member 13
Also, the limit switches 17a and 17b are actuated to detect the operation limit position of the rotary shaft 7. In this way, when each of the limit switches 16a, 16b; 17a, 17b operates, the operation of the motor 2 or 3 is normally stopped and the rotary shaft 6,
The rotation of 7 also stops, and the rotation of the wrist 20 around the S1 axis or the S2 axis stops at a predetermined position.

In addition, due to an electrical failure, the limit switch 16
When a, 16b; 17a, 17b do not operate, as for the rotary shaft 7, the end surface 13d or 13e of the male screw member 13 abuts the stopper member 18 or 19, so that the impact force is absorbed and the male screw member 13 is absorbed. While the rotation of the rotary shaft 7 integrated with the male screw member 13 is restricted at the same time as the movement of the rotary shaft 6 is restricted, the rotary shaft 6 has a stopper 21 or an end surface of the wrist 20 provided at an appropriate position. By touching 22
The rotation of the rotary shaft 6 is restricted, and the rotation of the wrist 20 around the S1 axis is mechanically restricted at a predetermined limit position.

As described above, according to the present embodiment, the bearings 33, 34 and the adjustment case 35, 34
By rotating the rotary shafts 6 and 7 directly connected to the speed reducers 4 and 5 in the axial direction by the 36, and holding them at predetermined axial positions using the set screws 37 and 38, the bevel gear 8a, 8b or 9
Backlash between a and 9b can be adjusted (including readjustment during maintenance) and removed much more easily than the conventional liner type. Further, since it is not necessary to separately provide a component such as a sliding key or a spline that causes rattling, the structure is simple, and at the same time, it is possible to save components and prevent a new rattling factor due to the use of extra components. .

Further, by removing the cover of the casing 1 on the sides of the bevel gear mechanisms 8 and 9 and using the rotation jig engaging holes formed in the bearing cases 33 and 34, the bearing cases 33 and 34 are simply rotated to cause backlash. Since the robot can be adjusted, the backlash adjustment (including readjustment) and removal can be performed from the outside after the robot wrist is assembled.

In the above embodiment, the case where the mechanism of the present invention is applied to the wrist 20 of the robot has been described, but the present invention is not limited to this, and may be applied to other joints having the same configuration. Applies as well.

[Effects of the Invention] As described in detail above, according to the backlash removing mechanism of the industrial robot of the present invention, the rotary shaft is moved in the axial direction by utilizing the margin of the speed reducer, and the predetermined position is maintained by the position holding mechanism. Since the backlash between the bevel gear of the output shaft and the bevel gear of the rotating shaft can be adjusted by holding the bevel gear of the output shaft in the axial position, it is extremely easy to adjust and remove the backlash between the bevel gears. In addition to that, because the structure is simple,
At the same time as saving the parts, it is possible to obtain the effect of preventing the occurrence of a new play due to the use of the extra parts.

In addition, the two bevel gears that mesh with the rotary shaft and the output shaft are integrally structured to prevent rattling, and the gear body having the two bevel gears is rotated by a screw to axially move the transmission shaft. Occurred because the backlash between the bevel gear of the output shaft and the bevel gear of the gear body was removed, and the bevel gear that meshed with the bevel gear of the output shaft moved from its original position for this removal. The increase in backlash and the backlash of the two bevel gears of the rotating shaft and the output shaft are simultaneously moved by moving the rotating shaft directly connected to the reducer and the bevel gear of the rotating shaft within the allowance range of the reducer. Since it can be removed, the backlash of the two sets of bevel gears can be easily removed, and a new play is not generated at all as compared with the case of using a spline or a key to add the backlash removing mechanism. Tsu there are bets, since the further secure the rear stage of the output side bevel gear in the axial direction, when used in wrist need not affect the positional relationship between the end effector, such as a welding torch.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 show a backlash removing mechanism of an industrial robot as an embodiment of the present invention, and FIG. 1 shows a joint of a robot to which the mechanism of this embodiment is applied. 2 is a cross-sectional view of a portion (I-I arrow cross-sectional view of FIG. 2), FIG. 2 is a II-II arrow cross-sectional view of FIG. 1, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 is a schematic view showing a backlash removing mechanism of a conventional industrial robot. In the figure, 1 ... Casing, 2, 3 ... Drive motor (rotational drive means), 4,5 ... Reducer, 6,7 ... Rotation shaft, 6a, 7a ... Stepped portion, 8, 9 ... Bevel gear mechanism, 8a , 8b; 9a, 9b ... Bevel gears, 10,11
… Sliding key, 12,13… Male screw member, 12a, 13a… Thread, 12
b, 12c; 13b, 13c ... end face of screw thread, 13d, 13e ... end face of male screw member, 14,15 ... fixing guide, 16a, 16b; 17a, 17b ... limit switch, 18,19 ... rubber stopper member, 20 ... Robot wrist, 21,22… rubber stopper, 23-26… bearing, 27,28
… Retaining ring, 29, 30… Rotating shaft (output shaft), 31, 32… Bolt,
33,34 ... Bearing case, 33a, 34a ... Stepped portion, 33b, 34b ... Threaded portion, 35, 36 ... Adjustment case, 35a, 36a ... Threaded portion, 37, 38 ...
Set screw, 39 ... Bevel gear mechanism.

Claims (1)

[Scope of utility model registration request] 1. A backlash removing mechanism for an industrial robot having two sets of bevel gear mechanisms between a speed reducer arranged in a casing of the robot and an output shaft, the speed reducer being directly connected to the speed reducer. A rotary shaft connected to the rotary drive means via a machine and having bevel gears at one end and parallel to each other, an output shaft having a bevel gear at one end, and the rotary shaft provided between the rotary shaft and the output shaft. A transmission shaft extending orthogonally to the axial direction, and a pair of gear members having two bevel gears that are axially supported by the transmission shaft and mesh with the bevel gear of the rotating shaft and the bevel gear of the output shaft, respectively. The gear member is provided so as to be movable in the axial direction of the transmission shaft by rotation of a screw screwed to the transmission shaft, and the rotation shaft includes the respective bearing cases of the rotation shaft and the casing. Between A position holding mechanism capable of holding the rotary shaft at a predetermined axial position is provided, and the bearing case is internally fitted and screwed into the position holding mechanism so as to be axially movable, and the position holding mechanism is provided around the bearing case. A backlash removing mechanism for an industrial robot, comprising a stop member, wherein the rotation shaft is moved within an axially movable margin in the speed reducer.