JP2541521B2 - Linear drive mechanism for industrial robots - Google Patents

Description

The present invention relates to a linear drive mechanism for linearly moving a movable part of an industrial robot.

[Conventional technology]

FIG. 2 shows a conventional drive mechanism for linearly moving a movable part (body or shaft) of an industrial robot. Bearing in casing 72
A ball screw nut 52 is screwed into a threaded portion 51 of a ball screw shaft 50 which is erected via 56, and the nut 52 has an arm.
The inner case 54 is fixed in parallel to the ball screw shaft 50 via 70. In addition, a toothed pulley 60 is attached to the lower end of the ball screw shaft 50.
Is fixed, and the toothed pulley 60 is connected via a toothed timing belt 62 to another toothed pulley 64 fixed to the tip of the drive shaft 66 of the servomotor 68 fixed below the casing 72. .

Due to the linear drive mechanism described above, the toothed pulleys 60,6
Servomotor 6 via 4 and toothed timing belt 62
The inner barrel 54 moves up or down together with the ball screw nut 52 by the rotational movement of the ball screw shaft 50 driven by 8.

In the upper part of this inner body, a vertical axis 80 that rotates around the vertical axis
Is provided, an arm 82 is extended through a drive unit 81 including a motor, a wrist portion 84 is provided at the tip of the arm 82, and a work hand 86 is provided at the tip. Has been done.

[Problems to be solved by the invention]

However, in the above-described conventional linear drive mechanism, it is necessary to dispose the toothed pulley 60 and the bearing 56 in series in the lower portion 58 of the ball screw shaft 50 in the longitudinal direction thereof.
The length of the threaded portion 51 for screwing together is inevitably short. Therefore, the movable stroke l of the inner case 54 is also shortened accordingly.
In order to lengthen the movable stroke l, it is necessary to lengthen the ball screw shaft 50 by that amount, and eventually the entire drive mechanism becomes long and large.

Therefore, in order to solve such a problem, the present invention makes it possible to increase the stroke of the movable part without changing the size of the entire linear drive mechanism, or to obtain a necessary stroke, a more compact size. It is intended to provide a linear drive mechanism.

[Pivot for solving problems]

In view of the above-mentioned object of the invention, the present invention uses a rotation-linear motion conversion mechanism, which is a movable part of an industrial robot, including a ball screw shaft and a ball screw nut, and a rotary driving force from a drive source to a toothed timing belt. A linear drive mechanism of an industrial robot that linearly moves between a storage position inside a housing and an upper position outside the housing by transmitting power to the rotation-linear motion conversion mechanism via a linear drive mechanism of an upper region of an inner chamber of the housing. A servo motor that forms the drive source is attached to the support portion in a vertical direction, and one toothed pulley is attached to its output shaft, and a rotary bearing is also fixed at a fixed position in the upper portion of the inner chamber of the housing. The other toothed pulley that is attached so as to be rotatable only through the timing belt and that transmits the rotation from the one toothed pulley via the timing belt; The ball screw nut is received in the center of the toothed pulley, and the ball screw nut has the lowest end side in the inner chamber of the housing and is screw-engaged with the ball screw shaft extending in the longitudinal direction. At the uppermost end of the ball screw shaft extending in the vertical direction, a straight vertical movement is possible between a retracted position retracted into the inner chamber of the housing and a raised position protruding upward from the inner chamber of the housing. The robot inner body which is fixed to the upper end of the robot inner body and moves up and down integrally according to the vertical movement of the ball screw shaft is provided as the movable part, and the ball screw shaft screwed to the ball screw nut is A ball screw portion is provided over the entire length between the uppermost end and the leg lower end, so that the vertical linear motion stroke of the robot inner body is made to extend over substantially the entire length of the ball screw shaft. Robot direct A line drive mechanism is provided.

[Action]

By moving the bearing and the rotary drive power transmission pulley from the ball screw shaft to the ball screw nut, it becomes possible to provide a screw over substantially the entire length of the ball screw shaft, and a ball screw nut that rotates at a fixed position. The linear stroke of the movable part can be lengthened in cooperation with each other.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 illustrates a linear drive mechanism of an industrial robot according to the present invention, which may be considered as a vertical sectional view of a base portion of the robot, for example. The rotational driving force of the servo motor 28 fixed to an upper position in the casing 32 by an appropriate fixing means is applied to the drive shaft 26 of the servo motor 28, the toothed pulley 24 fixed to the drive shaft 26, and the toothed pulley. The ball screw nut 12 is formed by forming another toothed pulley 20 which is transmitted to the toothed timing belt 22 wound around the toothed wheel 24 to engage with the toothed timing belt 22 and is rotated. The ball screw nut 12 is supported by the bearing 16 at an upper position in the casing 32 and can rotate only about the central axis.The ball screw shaft 10 is screwed onto the ball screw nut 12. It is configured to be able to move in a straight line. An inner shell 14 is fixed to the upper end 18 of the ball screw shaft 10 in parallel with the ball screw shaft 10 via an arm 30, and a screw is provided on the ball screw shaft 10 over the entire length of the remaining portion excluding the upper end 18. And forms the threaded portion 11.

As described above, the ball screw nut 12 and the servo motor 28 are installed at the upper position in the casing 32. Since the lower end of the ball screw shaft 10 can be lifted up to the position of the ball screw nut 12, the ball screw nut 12 and the servomotor must be used in order to lengthen the stroke of the ball screw shaft 10 and the stroke of the inner shell 14. It is desirable to set the installation position with 28 to the upper position in the casing 32 as much as possible.
If you install the ball screw nut 12 in such a position,
As described above, the ball screw shaft 10 provided with screws over substantially the entire length thereof has the threaded portion 11 longer than the conventional threaded portion 51 (Fig. 2). It is possible to obtain a linear stroke L that is longer than the conventional linear stroke 1 (FIG. 2) by utilizing the limit.

In addition, the inner body 14 which can obtain a long straight stroke in this way
At the upper end of the robot, a rotatable vertical axis, a drive unit, an arm, a wrist unit, and a hand are attached as in the conventional robot.

〔The invention's effect〕

As is clear from the above description, according to the present invention, since the screw portion of the ball screw shaft can be set to be long, a linear drive mechanism for an industrial robot that can extend the linear stroke with a short and compact structure is provided. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a linear drive mechanism of an industrial robot according to the present invention, and FIG. 2 is a schematic sectional view of a linear drive mechanism of a conventional industrial robot. 10 …… Ball screw shaft, 11 …… Screw part, 12 …… Ball screw nut, 14 …… Movable part (inner case), 18 …… Upper end, 20 …… Toothed pulley, 22 …… Toothed timing belt, 24 …… Toothed pulley, 26 …… Drive shaft, 28 …… Servo motor, 30…
… Arm, 32… Casing, L… Linear stroke.

Claims (1)

(57) [Claims] 1. A rotary part of an industrial robot using a rotation-linear motion conversion mechanism composed of a ball screw shaft and a ball screw nut, and a rotary drive force from a drive source via a toothed timing belt. In a linear drive mechanism of an industrial robot that linearly moves between a storage position inside a housing and an upper position outside the housing by transmitting to a conversion mechanism, a drive source is provided in a support portion in an upper region of an inner chamber of the housing. The servo motor to be formed is attached in a vertical orientation, and a pulley with one tooth is attached to its output shaft so that it can only rotate through a rotary bearing at a fixed position in the upper region of the inner chamber of the housing. The other toothed pulley that is attached and whose rotation is transmitted from the one toothed pulley via the timing belt is provided, and the other toothed pulley is provided at the center of the other toothed pulley. The ball screw nut is received, and the ball screw nut has a lowermost end in the inner chamber of the housing and is screw-engaged with the ball screw shaft extending in the longitudinal direction, and the ball screw nut is extended in the longitudinal direction. At the top end of the ball screw shaft,
The upper and lower parts of the ball screw shaft are fixed by fixing the upper end of the robot inner body, which is vertically movable between the retracted position retracted into the inner chamber of the housing and the raised position protruding upward from the inner chamber of the housing. The robot inner body that rises and falls integrally according to movement is provided as the movable portion, and the ball screw shaft screwed into the ball screw nut is a ball screw portion over the entire length between the uppermost end and the lowermost end. A linear drive mechanism for an industrial robot, characterized in that the vertical translation stroke of the inner body of the robot is made to extend over substantially the entire length of the ball screw shaft.