JPH0121241Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a backlash removal device for a bevel gear mechanism used mainly in the wrist of an industrial robot.

(Prior art) Conventionally, a tool unit mounting shaft in a direction perpendicular to the swing axis is pivotally supported in a swing case that constitutes the wrist of an industrial robot, and the swing case is used as a gear case inside the swing case. , a drive bevel gear connected to a drive shaft arranged concentrically with the swing axis and a driven bevel gear connected to the mounting shaft are arranged so as to mesh with each other, so that the tool unit can swing through the swing case. In addition, it is known that the drive shaft is capable of turning through both the bevel gears and the mounting shaft. Conventionally, a spring is provided on the back of the driving bevel gear or the driven bevel gear to bias it in the axially forward gear engagement direction to eliminate the backlash.

(Problem to be solved by the invention) In the above conventional technology, it is necessary to secure a space for placing the spring between the bevel gear biased by the spring and the case side wall on the rear side, and the case is large accordingly. Moreover, when replacing the spring or adjusting the spring force, it is necessary to disassemble the case and remove the bevel gear, resulting in the inconvenience of poor workability.

In order to eliminate such inconveniences, the present invention is a device that allows the spring for removing bumps to be placed without increasing the size of the case, and also allows the replacement and adjustment work to be easily performed from the outside of the case. Its purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a shaft rod extending coaxially from one of the bevel gears to the other end thereof, and also A recess is formed in the side wall of the gear case located at the axially forward end of the gear case, and the shaft rod is inserted into the recess and is attached to the recess by a spring. It is characterized by being biased forward in the axial direction.

(Embodiment) The present invention will be explained with reference to the illustrated embodiment in which the present invention is applied to a bevel gear mechanism of a robot wrist.

In the drawings, 1 is a robot arm, 2 is a fixed case fixed to the tip of the arm 1, and a cylindrical first drive shaft 3 and a second drive shaft 4 on its inner circumference are connected to the fixed case 2 in a horizontal direction. The first
Sprockets 3a, 4a are provided on the outer periphery of the intermediate portion of the drive shaft 3 and the shaft end of the second drive shaft 4, respectively, so that both the drive shafts 3, 4 can be driven independently on the respective sprockets 3a, 4a, Furthermore, a swinging case 5 connected to the first drive shaft 3 is pivotally supported at the lateral end of the fixed case 2, and a tool unit 6 is attached to the swinging case 5.
The extension of the axis of the mounting shaft 7 is the second drive shaft 4.
The drive bevel gear 8 connected to the second drive shaft 4 and the mounting shaft 7 are connected to the rocking case 5 as a gear case. A driven bevel gear 9 is accommodated, and both bevel gears 8 and 9 are engaged with each other.

In the case shown, the tool unit 6 consists of an arc welding unit, and includes a unit case 6c that pivotally supports a rotating shaft 6b to which a welding torch 6a is attached.
A drive motor 6 for driving the rotating shaft 6b with a belt is provided above.
d, and the unit case 6c is fastened to the outer end of the mounting shaft 7 at its bottom plate with a nut 10. In the drawing, reference numeral 6e indicates a power supply body that supplies power to the power supply sleeve 6f at the tail end of the welding torch 6a via a brush 6g, and the power supply body is fitted into the end of the swing case 5. Although the above is not particularly different from the conventional robot wrist part described above, in the illustrated embodiment, according to the feature of the present invention, from one of the bevel gears 8 and 9, for example, the drive bevel gear 8, to the other end coaxially with this A shaft rod 11 extending from the drive bevel gear 8 is provided on a lateral side wall of the swing case 5 located axially ahead of the drive bevel gear 8.
A recess 12 is formed inwardly toward the recess 12, and the shaft rod 11 is inserted into the recess 12.
2 is biased forward in the axial direction.

To explain this in more detail, in the illustrated example, a thrust bearing 11b is attached to the tip of the shaft rod 11 to prevent it from coming off with a nut 11a.
The spring 13 is compressed between the bearing 11b and the bottom of the recess 12, and the spring 13 causes the bearing 11b to
A biasing force is applied to the shaft rod 11, and therefore the driving bevel gear 8 connected thereto, in the occlusal direction with respect to the driven bevel gear 9 located at the axially front side, through the shaft rod 11 and the nut 11a.

In the drawing, reference numeral 14 indicates a cover provided on the outer surface of the side wall of the swing case 5 to cover the recess 12, and the spring 13
The cover 14 is removed during replacement or adjustment work. Reference numeral 15 indicates a limit switch which cooperates with the cam 16 on the shaft 11 to detect the rotational phase.

(Function) The function of the present invention will be explained based on the above embodiment. According to the rotation of the first drive shaft 3, the tool unit 6 is connected to the tool unit 6 via the swing case 5 about the horizontal axis of the shaft 3. According to the rotation of the second drive shaft 4, the rotation of the mounting shaft 7 via the drive bevel gear 8 and the driven bevel gear 9 causes the tool unit 6 to rotate about the longitudinal axis of the shaft 7. In this case, due to the biasing force of the spring 13 acting on the drive bevel gear 8 via the shaft rod 11 as described above, both the bevel gears 8 and 9 are elastically engaged without collapsing. In this way, the tool unit 6 can be controlled to turn with high precision.

(Effect of the invention) As described above, according to the invention, one of the driving bevel gear and the driven bevel gear is moved axially forward by the spring in the recess formed in the side wall of the gear case in the shaft rod protruding from the bevel gear. The free space in the axial direction of both bevel gears in the gear case can be utilized as a space for arranging the spring for removing the backlash, thereby reducing the size of the gear case.
In addition, the spring can be adjusted and replaced from the outer surface of the recess without disassembling the gear case, thereby improving work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of an example of a robot wrist equipped with the device of the present invention, and FIG. 2 is a cross-sectional view taken along the line -- in FIG. 5... Swinging case (gear case), 8... Driving bevel gear, 9... Driven bevel gear, 11... Shaft rod, 12... Recess, 13... Spring.

Claims (1)

[Scope of utility model registration request] In a gear case that houses a driving bevel gear and a driven bevel gear meshing with the driven bevel gear, a shaft rod is provided protruding from one of the bevel gears and coaxially extending forward, and a shaft rod of the one bevel gear is provided. A recess is formed in the side wall of the gear case located at the front in the axial direction, and the shaft rod is inserted into the recess and is attached to the recess by a spring. A deformation removal device for a bevel gear mechanism, characterized in that it is biased toward the front in the axial direction.