JPH03234488A - Rectangular coordinate type robot - Google Patents

Abstract

PURPOSE:To work a reaction required for the acceleration of a moving base as the shaft force of the driving shaft of each linear movement unit and extremely increase rigidity by providing such a constitution as situating a working position in a cross point in which each linear movement unit is crossed to each other at a right angle. CONSTITUTION:One linear movement unit 19 is driven and moved in a determined direction, and the other linear movement unit 24 is moved in the moving direction of the linear movement unit 19 while being supported by support bases 12a, 12b. Hence, the work position, or a working head is regularly situated in the cross point of the axial lines of both the linear movement units 19, 24 and directly driven by the respective linear units 19, 24. Therefore, the reaction of a force accelerating the masses of a tool shaft 26 and each linear operating unit 19, 24 acts on each linear movement unit 19, 24 as its shaft force.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a Cartesian robot.

(Prior Art) Conventional Cartesian coordinate robots have a rectangular parallelepiped operating area and have a simple structure, and are therefore widely used for assembling electronic parts and mechanical parts. This kind of Cartesian coordinate robot can be roughly divided into two categories. One of them is, as shown in a plan view in FIG. 7, a garter 2 whose both ends are supported by a tower-shaped pedestal 1 and which moves in the X direction along a linear guide 4 by a linear drive mechanism 5 and a drive motor 6. and a movable table 3 equipped with a tool elevating shaft (indicated by a working position P) that moves on the gutter 2 along a linear guide 4 in the Y direction perpendicular to the moving direction of the gutter 2. The other one, as shown in a plan view in FIG. A movable table 3 having the same structure that moves in the Y direction orthogonally thereto, and equipped with a processing head (indicated by working position P) consisting of a tool elevating shaft, etc.
is arranged. Both types were used depending on the required load, operating range, positioning accuracy, etc.

(Problem to be Solved by the Invention) However, in recent years, these Cartesian coordinate robots have been applied to devices called chip mounters that mount chip components onto printed circuit boards, and as a result, the conventional There is a growing demand for high-speed and high-accuracy work that cannot be achieved with these bots. In particular, in order to speed up the work, it is essential to increase the maximum speed and acceleration of each axis, such as the tool elevating axis. However, in conventional Cartesian coordinate robots, for example the one shown in FIG. 7, the drive for movement in the
Since the linear drive mechanism 5 is used at one end of the gutter 2, if the gutter 2 is started or stopped at a high acceleration/deceleration rate, bending vibrations as shown by the arrows in FIG. 7 will occur in the gutter 2. In particular, at the critical work position P, the vibration displacement of this bending vibration is amplified, which may lead to a significant drop in work accuracy.

Furthermore, in order to prevent this drawback, a method has been used in which a linear drive mechanism 5 is provided at the other end of the gutter 2 and both drive mechanisms are driven in synchronization. However, with this driving method, not only did the entire device become large-scale, but also the bending vibration of the gutter 2 still occurred. Furthermore, for example, even in the case shown in FIG. 8, the support in the Y-axis direction has a complete cantilever structure, so the rigidity is low, which causes bending vibration. In addition, in both the systems shown in FIGS. 7 and 8, the maximum speed of each axis such as the tool elevating axis is limited by the critical speed of the long ball screw of the linear drive mechanism 5 rotated by the drive motor 6. There was a problem that it could not be made too high.

The present invention has been made in view of the above points, and the processing head is supported by linear guides having both ends provided on opposite sides of the quadrilateral frame of the pedestal, and the processing head is suspended at the intersection of mutually orthogonal screw splines. By arranging the housing and driving each screw spline with a separate motor,
High rigidity, no vibration even at high acceleration/deceleration, high positioning accuracy, and the maximum speed of each axis can be set high.
Therefore, the purpose of this invention is to provide a Cartesian coordinate robot that can speed up work.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, in the Cartesian coordinate robot of the present invention, a first linear motion unit having a movable base and a second linear motion unit having another movable base are separated from each other. The movable tables are connected and integrated so that their axes are perpendicular to each other, and a processing head is disposed near the connection point, and at least one of both ends of the first linear movement unit is connected to the second linear movement unit. The second linear movement unit is supported by a support stand provided to move in parallel to the movement direction, and at least one end of the second linear movement unit is provided to move in parallel to the movement direction of the first linear movement unit. It is supported by a support stand.

(Function) In the Cartesian coordinate robot configured as above,
When one linear movement unit is driven to operate in a predetermined direction, the other linear movement unit is supported by the support base and moves in the movement direction of the one linear movement unit. As a result, the working position, ie the processing head, is always located at the intersection of the axes of the two linear units and is directly driven by each linear unit. For this reason,
The reaction force of the force accelerating the mass of the tool axis and each linear motion unit is the axial force (axial compressive force) on each linear motion unit.
It acts as.

(Example) Hereinafter, an example of the Cartesian coordinate robot of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, there are near guides 7a on each opposing side of the quadrilateral frame on the upper surface of the tower-shaped pedestal 1.

7b, 8a, and 8b are provided, and linear guide bearings 9 are provided on these linear guides 7a, 7b, 8a, and 8b.
Support stands 11a, ll via a, 9b, 10a, 10b
b, 12a, and 12b are movably arranged along a linear guide. In addition, support stands 11a, llb, 12a
, 12b each have a screw spline 13.23 fixed thereto. Furthermore, as shown in FIGS. 3 to 15, the screw spline 13 has a cylindrical shaft cross section, and a pole screw groove 13a for accommodating the ball B and a ball spline groove 13b are formed on the outer periphery of the screw spline 13. A movable table 14 having a shape of
It is supported by 3.

Note that the spline bearing 15 is secured within the housing H by a flange. In addition, the moving table 14 has a bearing 16.
A pole screw nut 17 that engages with the pole screw groove 13a is rotatably supported. Note that the bearing 16 is secured to the housing H by a spacer 16A. A toothed belt pulley 18 is fixed to this ball screw nut 17, and the housing H is fixed to the ball screw nut 17 by a cover plate 14A.
Further, a drive motor 19 is fixed to the housing portion of the moving table 14, and a toothed belt pulley 21 is fixed to its output shaft 20, and both toothed belt pulleys 18, 21 A toothed belt 22 is wound between them to transmit the rotational force of the drive motor 19 to the ball screw nut 17. Furthermore, screw spline 1
Support stands 11a and llb that move along linear guides 7a and 7b are fixed to both wheel ends of 3. In this way, the first linear motion unit of the Cartesian robot is configured.

On the other hand, at both wheel ends of the screw spline 23, there are support stands 12a, 12 that move along the linear guides 12a, 12b.
b is fixed to the screw spline 23, and a movable base 25 is attached to the movable base 1 by means similar to the above-described movable base 14.
It is integrally formed and supported so as to be orthogonal to the movement of 4. Further, a drive motor 24 is fixed to the housing portion of the movable table 25, and the rotational force of the drive motor 24 is transmitted to the ball screw nut 17 by the same means as the movable table 14. In this way, the second linear motion unit of the Cartesian coordinate robot is constructed. Further, a tool shaft 26 is suspended from the housing of the movable table 25 at the intersection of both screw splines 13.23 to which a tool, which is a processing head, is attached. The movable tables 14 and 25 configured in this manner constitute an integrally formed housing H and move as one.

The operation of the embodiment of the Cartesian coordinate robot of the present invention constructed in this way will be explained with reference to FIGS. 1 and 2. First, when the drive motor 19 attached to the movable base 14 is rotated, the rotational force of the output shaft 20 of the drive motor 19 is transmitted to the ball screw nut 17 via the toothed belt 22. The linear movement unit moves in the axial direction of the screw spline 13, that is, in the X direction shown in FIG. 1, along the linear guides 7a and 7b via the balls. At the same time, the movable base 25 that is integrally coupled with the movable base 14 and the screw spline 23 that supports the movable base 25 are also supported by the linear guides 8a and 8b, with the support bases 12a and 12b fixed to both ends thereof. Since it is supported via the linear guide bearings 10a and 10b, the '1s2 linear motion unit having the moving table 25 also moves in the X direction. Furthermore, when the drive motor 24 attached to the movable base 25 is driven, the movable base 25 moves along the screw spline 23 by the same movement as the movable base 14.
The both ends of the shaft are connected to the linear guide 7a.

Since it is fixed to the support bases 11a and 11b supported on the linear guide bearings 9a and 9b on the 7b, the first linear motion unit moves in the axial direction of the screw spline 23 together with the movable base 14 and the screw spline 13. ,
That is, it moves in the Y direction.

Therefore, the tool and its tool axis (elevating axis) 26
The axial center of , that is, the working position (point) P is
It is always located at the intersection of the screw spline 13 and the screw spline 23, which are perpendicular to the plane). As a result, both axial ends of the screw splines 13 and 23 are supported by the linear guides 7a, 7b, 8a, 8b of the pedestal 1, and
As it is moved, the reaction force of the force for accelerating the mass of the tool and its lifting shaft 26 acts as an axial force on the respective screw splines 13 and 23.

Therefore, this acceleration force no longer acts in the bending direction of the screw spline 13.23, which has low rigidity, and even if the moving platform is started and stopped at a high acceleration/deceleration rate, bending vibration of the screw spline 13.23 is extremely unlikely to occur. It becomes less.

Furthermore, since a highly accurate pole screw is directly used to determine the distance from the gantry 1 to the working position P, extremely high working accuracy can be achieved. Furthermore, since the moving table 14.24 is moved by rotating the ball screw nut door, there is no critical speed restriction that would be an obstacle when rotating a long pole screw, and the linear motion unit can operate at high speed. Become.

In this example, a screw spline was used as the linear drive mechanism of the moving table, but a rack and pinion were used instead of the screw spline, and the pinion and drive motor were arranged on the moving table to form a linear movement unit. It's okay. Further, when the mass of the tool and the lifting shaft (tool shaft) is small, the function of the ball spline to support their weight becomes less important, and therefore only the pole screw may be used instead of the screw spline. Furthermore, in this embodiment, two orthogonal screw splines were supported by a turret-shaped frame, but as shown in FIG. 6, in other embodiments,
One or both of the Y directions have a cantilever structure, and
The screw spline may be supported by a frame having a U-shaped or L-shaped planar shape. In the embodiment shown in FIG. 6, the names of parts common to those in the embodiment shown in FIG. 1 are given the same reference numerals, and their explanations are omitted.

In addition, when each linear movement unit is arranged in a rectangle, the short side screw spline may be made into a rigid structure and the long side screw spline may be made into a flexible structure in order to reduce the weight of the whole.

〔Effect of the invention〕

According to the present invention, two linear motion units composed of a drive motor, a linear drive mechanism, and a moving table are integrated and coupled together so that the parts of both moving tables are perpendicular to each other, and the processing head is placed near the coupling point. In addition, both ends of each linear motion unit are fixed to a support base supported on a linear guide provided on the frame, so that the working position (point) of each linear motion unit is always fixed. They will be located at orthogonal intersections. As a result, the reaction force required to accelerate the moving table is the axial force (axial compressive force) of the drive shaft of each linear motion unit.
The rigidity is extremely high, and the displacement is smaller than that of conventional bending rigidity, which reduces vibrations caused by starting and stopping the moving platform due to high acceleration/deceleration, and improves indexing accuracy due to the linear motion unit. Since this directly corresponds to the positioning accuracy of the working position, high positioning accuracy can be obtained. Furthermore, since the moving table is moved by rotationally driving the nut of the pole screw, the maximum speed can be set extremely high, which has the effect of providing a Cartesian coordinate robot that can speed up work.

Figure 2 is a plan view of the example, Figure 3 is a partial cross-sectional view of the pole screw drive part of the linear drive unit, Figure 4 is a detailed side view of the screw spline, and Figure 5 is its cross section. 6 are plan views of other embodiments of the Cartesian coordinate robot of the present invention, and FIGS. 7 and 8 are plan views of conventional Cartesian coordinate robots.

1... Frame, 7a, 7b, 8a, 8b=... Linear guide, lla, llb, 12a, 12b-... Support stand,
13.23...Screw spline, 14.25...
・Moving table, 19.24... Drive motor.

Claims (1)

[Claims] A first linear movement unit having a moving table and a second linear movement unit having another moving table are integrated by connecting the respective moving tables so that their respective axes are perpendicular to each other, and a processing head is placed near the connecting point. and at least one end of both ends of the first linear motion unit is supported by a support stand provided so as to move in parallel to the operating direction of the second linear motion unit, and A Cartesian coordinate robot, characterized in that at least one end of both ends of a two-linear movement unit is supported by a support stand provided so as to move in parallel to the movement direction of the first linear unit.