JPH0616683Y2 - Trajectory control mechanism for processing tools - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) This invention is attached to the wrist part of a robot, so that a processing tool such as a laser torch can draw any shape such as a circle, an ellipse, or a square at its center. The present invention relates to a trajectory control mechanism of a processing tool for operating the tool.

(Prior Art) Recently, robots with a large number of joints and a large degree of freedom have been used for cutting work by laser and applying work such as sealant and grease.

By the way, when cutting a work into a circle by a multi-joint robot, it is necessary to move a processing tool such as a laser torch attached to the wrist of the robot so that the center of the processing tool moves in a circle. To control the trajectory, it is common to use the circular arc interpolation function of the robot.

(Problems to be solved by the invention) However, since the resolution of each axis and the locus calculation speed of the CPU are limited in the circular interpolation of multi-axis synthesis, there is a problem that the minimum radius of the circle that can be locus controlled is limited. However, it is necessary to reduce the operation speed in order to maintain the locus accuracy, and there is a problem that the machining efficiency is reduced.

An object of the present invention is to provide a trajectory control mechanism for a processing tool which has no limitation on the minimum radius of a circle which can be trajectory controlled, and which can easily set the trajectory and enhance the accuracy of the trajectory and the operation speed.

(Means for Solving the Problems) The present invention provides a rotating member rotatably supported by a base through a supporting member, and an outer periphery of the rotating member, which is concentric with the rotating member and rotates integrally with the rotating member. A first gear, and a ring-shaped second gear that is disposed adjacent to the rotating member and concentric with the rotating member, and that has inner teeth and outer teeth that are independently rotatable with respect to the rotating member and the first gear, The pinion, which meshes with the inner teeth of the second gear and is rotatably supported by the rotating member by the shaft, is provided so as to rotate integrally with the pinion, and the processing tool is placed at a position eccentric to the rotation center of the pinion. A first holding means for holding the holding gear; a first driving means for meshing with the first gear to rotate the same; and a second driving means for meshing with the outer teeth of the second gear to rotate the outer teeth. The first drive and the second gear are moved relative to each other by the two drive means. By rotating the rotating member, the eccentric amount of the center of the processing tool with respect to the center of rotation of the rotating member is arbitrarily set, and the first and second driving means rotate the first gear and the second gear in synchronization with each other. The center is the center of rotation of the rotating member,
The gist is a trajectory control mechanism of a processing tool configured to draw a circle having the eccentricity as a radius.

(Operation) The point where the center of the processing tool coincides with the center of rotation of the rotating member is the origin of the processing tool, and in the state where the center of the processing tool is located at the origin, the first drive means or the second drive means causes the first gear and the first gear When the two gears are rotated relative to each other by a predetermined angle, the pinion supported by the rotating member rotates about the predetermined angle according to the rotation angle, and the holder and the processing tool connected to the pinion rotate integrally with the pinion. As a result, the center of the working tool is eccentric with respect to the center of rotation of the rotating member, and the eccentricity of the center of the working tool is arbitrarily changed by changing the relative rotation angle between the first gear and the second gear. Can be set.

Next, when the first drive means and the second drive means rotate the first gear and the second gear in synchronization with each other, the pinion cannot rotate, so that the position of the pinion is fixed with respect to the second gear and the rotating member. In this state, they rotate as a whole around the rotation center of the rotating member. Thereby, the processing tool can be operated so as to draw a circle whose center is the rotation center of the rotating member and whose eccentricity is the radius. Then, if the rotation speeds of the first gear and the second gear are controlled to change the eccentric amount of the processing tool center,
It is also possible to operate to draw an arbitrary figure such as an oval other than a circle or a square.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.

A trajectory control mechanism A for controlling a trajectory of a processing tool K such as a laser torch so that its center draws an arbitrary figure such as a circle, an ellipse or a square is a wrist part R of a robot whose position and orientation are controlled by a CPU. Assembled to.

The base 1 of the trajectory control mechanism A has a wrist part R of the robot at one end.
And the like, and a circular opening 1b is formed at the other end, and the servo motor 1 to be described later is provided on both sides of the opening 1b.
Motor mounting seats 1c and 1d for mounting 7, 18 are integrally formed to project.

Below the opening portion 1b of the base 1, a bottomed cylindrical rotating member 3 having a projecting edge 3a on its outer periphery is rotatably supported via a supporting member 2. The supporting member 2 for supporting the rotating member 3 is formed in a stepped cylindrical shape corresponding to the rotating member 3, and supports the thrust load from the protruding edge 3a of the rotating member 3 via the bearing 4 at the stepped portion. In addition, the small diameter portion supports the radial load of the rotating member 3 via the bearing 5, and the large diameter portion is fixed to the lower surface of the base 1. Further, in the large-diameter portion of the support member 2, two window holes 2a, 2b are provided just below the motor mounting seats 1c, 1d of the base 1 and at positions corresponding to a first gear 6 and a second gear 8 which will be described later. Are separated from each other.

A first gear 6 having teeth on its outer peripheral surface is fixed to the projecting edge 3a of the rotating member 3 concentrically with the rotating member 3 by means of screws 7, and above the first gear 6 is adjacent to the rotating member 3. A ring-shaped second gear 8 having teeth 8a and 8b on the inner peripheral surface and the outer peripheral surface is concentric with the rotating member 3, and the rotating member 3 and the first member
It is arranged so as to be independently rotatable with respect to the gear 6. In order to dispose the second gear 8 in this way, a ring-shaped concave groove 8c is formed on the lower surface of the second gear 8, and the concave groove 8c is fitted into the outer periphery of the upper end of the rotating member 3 and has an L-shaped cross section. The ring-shaped thrust metal 9 is fitted slidably. Further, a bearing 10 is provided between the upper surface of the second gear 8 and the base 1 to prevent the second gear 8 and the thrust metal 9 from being separated from each other and to smoothly rotate the second gear 8. The bearing 10 is held in place by a cylindrical bearing retainer 11 fitted and fixed to the peripheral edge of the opening 1b of the base 1.

A shaft 12 is erected on the bottom 3b of the rotating member 3 at a position away from the center in parallel with the rotation center a of the rotating member 3, and the shaft 12 has a pinion 13 that meshes with the internal teeth 8a of the second gear 8.
Also, one end of a holder 15 that is connected to the pinion 13 and a pin 14 and rotates integrally with the pinion 13 is rotatably supported. The hollow shaft 16 is fixed to the other end of the holder 15 by positioning the center portion c on an arcuate locus b centered on the shaft 12 and having the radius between the shaft 12 and the rotation center a of the rotating member 3 as a radius. There is. The hollow shaft 16 penetrates the bottom portion 3b of the rotary member 3 and projects downward, and the processing tool K is concentrically attached to the lower end thereof. For this reason,
The bottom portion 3b of the rotating member 3 is provided with an arc-shaped elongated hole 3c having the shaft 12 as a center and a radius between the shaft 12 and the rotation center a of the rotating member 3 as a radius. 13, holder 15 and hollow shaft 16
Are rotatable about the shaft 12. In the case of the illustrated example, the processing tool K is a laser torch, and an optical fiber cable for guiding a laser beam serving as a heat source for processing is connected to the laser torch through the hollow portion of the hollow shaft 16.

On the other hand, on the motor mounting seats 1c and 1d of the base 1, a first servomotor 17 and a second servomotor 18 for rotationally driving the first gear 6 and the second gear 8 are mounted, respectively. The drive gears 19 and 20 fixed to the output shafts of 17 and 18 are the window holes 2a of the support member 2,
It meshes with the first gear 6 and the second gear 8 through 2b.
In the figure, 21 is a limit switch for detecting the original position of the first gear 6, that is, the rotary member 3 which is integral with the first gear 6, and 22
Is a dog for operating the limit switch 21, 23 is a limit switch for detecting the original position of the second gear, and its actuator 23a passes through a window hole 2c provided in the large diameter portion of the support member 2. It is located in the support member 2.
Reference numeral 24 is a pin projecting from the second gear 8 for operating the limit switch 23.

Next, the operation of the above embodiment will be described.

In the drawing, the central portion of the hollow shaft 16, that is, the center c of the processing tool K (hereinafter referred to as the processing tool center c) coincides with the rotation center a of the rotating member 3, and this point is the origin of the processing tool center c. As a result, the original positions of the first gear 6 and the second gear 8 are respectively determined.

In this state, when the first servo motor 17 is stopped, only the second servo motor 18 is operated to drive the second gear 8 to rotate relative to the first gear 6 by a predetermined angle. Is stopped, the inner teeth 8 of the second gear 8
The pinion 13 that meshes with a rotates about the shaft 12 by a predetermined angle, and the holder 15 and the hollow shaft 16 that are connected to the pinion 13 at one end rotate integrally with the pinion 13 as shown by the chain double-dashed line in FIG. As a result, the processing tool center c
Is about the shaft 12, and the rotation center a of the shaft 12 and the rotating member 3 is
It is displaced to c ′ on an arcuate locus b whose radius is the inter-distance and is eccentric to the rotation center a of the rotating member 3 by a predetermined amount, and the relative rotation of the first gear 8 with respect to the first gear 6. By changing the angle, the eccentricity e of the processing tool center c can be set arbitrarily.

Next, with the predetermined deviation amount e set as described above, both the first and second servomotors 17 and 18 are operated to synchronize the first gear 6 and the second gear 8 with each other. When rotationally driven, the first gear 6 and the second gear 8 rotate integrally, so that the pinion 13 cannot rotate, and the holder 15 and the hollow shaft 16 are fixed in position with respect to the rotary member 3. The rotary member 3 rotates integrally with the rotary member 3 around the rotation center a. Accordingly, the movement locus of the processing tool center c ′ is controlled so as to draw a circle centered on the rotation center a of the rotating member 3 and having the radius of the eccentricity e.

When the first gear, that is, the rotating member 3 makes one revolution and returns to the original position, the limit switch 21 detects this and
The second servo motors 17, 18 are stopped. Second
After the first gear 6 returns to the original position, the gear 8 operates in the opposite direction to the second servomotor 18 when the deviation amount is set,
The limit switch 23 detects the original position of the second gear 8 and stops the second servomotor 18, thereby returning to the original position.

Further, the first gear 6 and the second gear 8 are not rotationally driven in synchronization, but a relative speed difference is given to the rotations of the first gear 6 and the second gear 8 so that the deviation amount e of the machining tool center c is increased. If the first gear 6 and the second gear 8 are rotationally driven while changing, the movement locus of the processing tool center c can be controlled so as to draw an arbitrary figure such as an oval or a square in addition to the circle.

(Effect of the Invention) According to the present invention, there is no limitation on the minimum radius of the circle that can control the locus, and the locus can be set steplessly and easily within the range of the inner diameter of the ring gear, and the locus accuracy and the radius holding accuracy can be improved. Therefore, the locus accuracy is high and high-speed operation is possible. Further, since the entire structure is lightweight and compact, the robot can be easily attached to the wrist or the like.

Furthermore, when the trajectory control mechanism of the present invention is attached to the wrist of the robot, the teaching point is compared to the case where the work tool is operated so that its center draws a circle using the circular arc interpolation function of a normal robot. Can be reduced. That is, at least five teaching points are required in the circular interpolation teaching, whereas in the robot having the trajectory control mechanism of the present invention attached to the wrist, only the teaching of the center of the circle and numerical setting of the radius are required. Therefore, in combination with the fact that the trajectory control mechanism of the present invention can operate at high speed, there is an effect that the processing efficiency of the processing tool can be significantly improved.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a partially cutaway side view and FIG. 2 is a plan view. 1 ... Base 2 ... Supporting member 3 ... Rotating member 6 ... First gear 8 ... Second gear 12 ... Shaft 13 ... Pinion 15 ... Holder 16 ... Hollow shaft 19 ... Drive gear (first 1 drive means) 20 ... drive gear (second drive means)

Claims (1)

[Scope of utility model registration request] 1. A rotating member rotatably supported by a base via a supporting member, a first gear concentric with the rotating member on the outer periphery of the rotating member, and rotating integrally with the rotating member, and a rotating member. A ring-shaped second gear, which is disposed concentrically with the rotating member and is concentric with the rotating member, and has an inner tooth and an outer tooth independently rotatable with respect to the rotating member and the first gear, and meshes with the inner tooth of the second gear. A pinion that is rotatably supported by a rotating member by a shaft, a holder that is provided so as to rotate integrally with the pinion, and that holds the processing tool at a position that is eccentric to the rotation center of the pinion; and a first gear. Meshes with the first drive means for rotating the same and the outer teeth of the second gear,
A trajectory control mechanism for a processing tool, comprising: a second drive unit that rotationally drives this.