Machine element or mechanism – Gearing
Patent
1986-12-09
1988-11-15
Braun, Leslie A.
Machine element or mechanism
Gearing
F16H 3700
Patent
active
047840145
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a robot joint with an electric drive motor and a reduction gear (harmonic drive). In a known robot joint of this type the assembly flange of the flexibly deformed outer gear ring and the assembly area of the one robot part facing the same are provided with plane faces which are braced against each other with a plurality of mounting screws, whereby the torque is transmitted by the friction locking between the plane faces of the parts, as well as by the mounting screws themselves which are designed as tight-fit screws and/or by additional set pins. In these embodiments it may occur that the bores for receiving the tight-fit screws or setpins open out after a longer period of operation of the robot joint, so that an accurate positioning of the robot parts is no longer assured.
SUMMARY OF THE INVENTION
In contrast thereto, the device in accordance with the invention is advantageous in that in highly stressed robot joints a connection between the assembly flange of the flexibly shaped outer gear ring and the one robot part is maintained absolutely free from play over a long time of operation.
In robot joints, wherein the assembly face for the assembly flange of the flexibly deformed outer gear ring is formed in a bushing pressed into the one robot part, it is suggested that the bushing is additionally secured against twisting by means of a knurled gear in the receiving bore of the one robot part.
A compact and bending resistant mounting is obtained if the one robot part is mounted rotatably on the other robot part by at least one pretensioned roller bearing.
In robot joints, whose robot parts consist of light metal and wherein a steel bushing is pressed into the one robot part, on which the one half of the front gear is formed, a wear resistant embodiment is obtained if the inner barrel ring of the pretensioned roller bearing is mounted on the steel bushing.
BRIEF DESCRIPTION OF THE DRAWING
One exemplified embodiment of the invention is illustrated in the drawing and is explained in more detail in the subsequent description. The single figure illustrates a partial section through the exemplified embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The robot joint connects a support 10 with a robot arm 12 which is pivotably mounted in the support 10 around a joint axis 14. The mounting is performed free from play by means of a pretensioned roller bearing 16, preferably a cross roller bearing, whose inner barrel ring or race 18 is mounted on a shoulder 20 of a steel bushing 22 which is pressed into a bore 24 of support 10. The outer barrel ring or race 26 of the roller bearing 16 sits firmly in a recess 28 of the robot arm 12 and is mounted thereon free from play by screws 30.
An electromotor 32 is mounted coaxially with respect to the joint axis 14 on support 10, whose downwardly extending power output axis 34 is fixedly connected with a shaft 36. This shaft extends through the steel bushing 22 and a central bore 38 in the robot arm 12 and is rotatably mounted at its free end on a lid 40 which is fixedly screwed to the robot arm 12. The annular slot 42 between shaft 36 and the steel bushing 22 is sealed by a packing ring 44 against the upper segment of bore 24 which is not filled out by bushing 22.
A drive disk 46 with an elliptical outer shape is fixedly mounted on the drive shaft 36 in the area of bore 38 of the robot arm. On the outer circumference of disk 46 an elliptical ball bearing 48 is mounted. These and the elements which are described in the following are parts of a reduction gear which is named a harmonic drive, through which the electromotor 36 pivots the robot arm 12 with respect to the support 10. Such drives are known, so that the subject drawing is limited to the sectional view of its elements.
On the drive disk 46 with the mounted elliptical ball bearing 48 (wave generator) an elastically deformable, externally toothed ring 50 (flexspline) is mounted. The ring 50 is connected with a rigid assembly or mounting flange 54 by means of a
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Bruns Joachim
Gosdowski Gerhard
Kettner Andreas
Braun Leslie A.
Novais David
Robert & Bosch GmbH
Striker Michael J.
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