JPH06114660A - Floating unit - Google Patents

Abstract

PURPOSE:To provide a floating unit with which directional restrictions about the reactive force capable of being absorbed are eliminated and which is improved so that reactive force in any direction can be absorbed any as desired. CONSTITUTION:A floating unit includes a body 1 of floating unit secured to a robot arm 9 and assuming a box shape, two beams 2 which consist of a resilient substance, are fixed rotatably to the inside of the unit body 1, and intersect each other, wherein the intersecting point 3 is secured mutually, and a tool holder 6 of rigid material extending from the plane formed by the two beams 2 from the intersecting point 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a connecting tool (hereinafter referred to as a floating unit) for elastically connecting a robot arm and a tool. In particular, the present invention relates to an improvement that eliminates the restriction on the direction of the reaction force that can be absorbed by the floating unit (reaction force received by the tool), can freely absorb the reaction force in any direction, and improves the cushioning performance.

[0002]

2. Description of the Related Art In a robot controlled by an NC controller or the like, machining, finishing of cast products,
A floating unit as shown in FIG. 4 has been used for attaching a tool holder when deburring or beading is performed in a finishing process such as welding.

See FIG. 4. FIG. 4 is a view showing a conceptual configuration when a tool holder is attached to a robot arm using a floating unit according to a conventional technique. In FIG. 4, 6 is a tool holder, 7 is a tool, and 8 is a workpiece. 1
0 is a rotation center of the floating unit, 11 is a stopper, 12 is a compression spring, 13 is a fulcrum of the compression spring, F is a force applied to the tool 2, and f is a force applied to the tool holder 6. Is.

Here, an assembly of a member that supports the rotation center 10, a stopper 11, a compression spring 12, and a member that supports the fulcrum 13 of the compression spring is supported by the robot arm as a floating unit. In other words, the robot arm (not shown) supports the tool holder 6 by fixing the floating rotation center 10, the stopper 11 and the fulcrum 13 of the compression spring at four points. FIG. 4 shows a positional relationship at the time of starting machining, and the tool holder 6 is positioned by the stopper 11. When the robot performs deburring and bead removal in the finishing process, the robot arm (not shown) is pressed downward. At this time, the tool 7 receives the reaction force F at the contact point (machining point) between the tool 7 and the workpiece 8. This reaction force F causes the tool 7 and the tool holder 6 to move the floating rotation center 10
Floating in the clockwise direction with respect to the center as indicated by arrow A, the compression spring 12 is compressed. Due to this compression, the compression spring 12 generates a force f and floats until it balances the force F. For example, if a robot arm (not shown) is pressed further downward in order to increase the amount of deburring, the force F increases, and the force is largely rotated and balanced.

[0005]

By the way, in the finishing process such as deburring, the workpiece 8 moves in the direction perpendicular to the paper surface (see FIG. 4).
At the processing point, it receives a force in the direction perpendicular to the paper surface. Moreover, since the size of burrs or the like is not constant, the force (see FIG. 4) in the direction perpendicular to the plane of the drawing greatly varies.
Since the floating unit according to the conventional technology cannot absorb the force in the direction perpendicular to the paper surface, the tool 7 and the floating rotation center 10 receive this force, and in extreme cases, the tool 7 may be damaged. . Therefore, it is necessary to drive the robot arm so as to limit the force (see FIG. 4) in the direction perpendicular to the paper surface to a certain value or less. Further, when the inclination of the surface to be processed of the workpiece 8 is not constant, it is necessary to drive the robot arm so that the pressing direction of the tool 7 against the workpiece 8 is changed according to the inclination of the surface to be processed. In any case, it is necessary to teach the robot the movement of the robot arm so as to satisfy these conditions.

Further, when the lower surface of the workpiece 8 is processed instead of the upper surface of the workpiece 8 as described above, the reaction force F is downward (direction opposite to that in FIG. 4). In this case, since the tool holder 6 hits the stopper 11,
In this state, the floating unit does not function as limited.

An object of the present invention is to eliminate these drawbacks, and it is an object of the present invention to provide a floating unit having a simple mechanism and an increased degree of freedom in the moving direction of the tool holder.

[0008]

The above object is to fix a robot unit (9) to a box-shaped floating unit body (1) and to the inside of the floating unit body (1) so as to be rotatable. Formed by two beams (2) made of an elastic body and the two beams (2) from the intersection points (3), which intersect each other and the intersection points (3) are fixed to each other. Achieved by a floating unit having a rigid tool holder (6) extending from the surface to be treated.

[0009]

In the floating unit according to the present invention, since the tool holder 6 is made of an elastic material and is fixed to the intersecting body of the two rotatable beams 2, the force F (see FIGS. 2 and 3).
No matter which direction is applied, the force F is absorbed by each of the two beams 2 bending or rotating, so that the tool 7 is not damaged, and the inclination of the surface to be processed is not increased. It is not necessary to teach the robot the movement of the robot arm, which was required in the past, because it is not necessary to change the processing conditions in response to the change in

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A floating unit according to an embodiment of the present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a diagram showing a conceptual configuration when a tool holder is attached to a robot arm using a floating unit according to an embodiment of the present invention. In FIG. 1, 1 is a floating unit body, 2 is a beam made of an elastic body, and 3 is an intersection of the beams 2. 4 is a ball bearing that supports this beam 2, and 5 is this beam 2
It is a stopper. 6 is a tool holder, 7 is a tool, 8 is a workpiece, and 9 is a robot arm.

The robot arm 9 supports the floating unit body 1. Each of the two beams 2 has a circular cross section, both ends thereof are rotatably supported by ball bearings 4, and the range in which they can slide is limited by a stopper 5. The two beams 2 are orthogonal to each other, and are fixed so that the center of each beam 2 is the intersection 3. A tool holder 6 is fixed to the intersection 3 so as to be flush with the one beam 2. FIG. 1 shows the positional relationship before the machining is started. The beam 2 made of an elastic body is linear and positions the tool holder 6.

FIG. 2 is a schematic diagram when the floating unit according to one embodiment of the present invention is pressed downward. 2A is one beam and 2B is the other beam. F is the force applied to the tool, l is the length of the beam 2, ls is the vertical distance from the intersection 3 of the beam 2 to the machining point, and lr is the horizontal distance from the intersection 3 of the beam 2 to the machining point. Is the deflection angle, θ is the deflection angle, and lf is the floating amount.

When the robot performs deburring and bead removal in the finishing process, the floating unit is pressed downward. At this time, the tool receives a reaction force F at the contact point between the tool and the workpiece. The reaction force F causes the tool and the tool holder to rotate in the plane including the beam 2A on one side and the machining point in the clockwise direction about the intersection point 3 as a center, and the clockwise rotation moment Mo (Mo = F · lr) and the intersection point 3 Receives a force F that pushes upward.

FIG. 2 shows the positional relationship when the rotational moment Mo is received. One beam 2A is deflected by the rotational angle Mo and the other beam 2B is rotated by the deflection angle θ. The bending angle θ is expressed by the following equation.

[0016]

[Equation 1] Here, E: Young's modulus of the beam 2A _Iz : Second moment of area of the beam 2A

The floating amount lf is represented by the following equation.

[0018]

[Equation 2]

Although not shown, the two beams 2A and 2B move so as to be convex upward by a force F that pushes the intersection 3 upward.

FIG. 3 is a schematic diagram when the floating unit according to one embodiment of the present invention is pressed in a direction perpendicular to the paper surface.
F'is the force applied to the tool and θ'is the deflection angle. In the finishing process such as deburring, the workpiece moves in the direction perpendicular to the paper surface. At this time, the tool receives a force F'in the direction perpendicular to the paper surface at the processing point in addition to the force F. become. In this case, the rotation moment Mo '(Mo' = F '.
ls) and a rotational moment Mo ″ (Mo ″ = F ′, not shown) about the intersection 3 in the plane formed by the two beams 2.
・ Lr)

This rotation moment Mo 'causes one beam 2A to rotate by a deflection angle θ'and the other beam 2B bends by this rotation moment Mo' by a deflection angle θ '. The deflection angle θ'is

[0022]

[Equation 3] However, E ': Young's modulus of the beam 2B _Iz ': Second moment of area of the beam 2B

Although not shown in the figure, the two beams 2A and 2B are bent so that the tool holder 6 is rotated by a rotational moment Mo "about the intersection 3 in the plane formed by the two beams 2. Mu.

In a finishing process such as deburring by a robot, a force obtained by combining the force F and the force F'described above is applied to the processing point. At this time, if the two beams 2 are orthogonal to each other as shown in this embodiment, the Young's modulus E of the beam 2A and the geometrical moment of inertia I _{z of the} beam 2A with respect to the force F are obtained. Since the Young's modulus E ′ of the beam 2B and the geometrical moment of inertia I _z ′ of the beam 2B can be selected independently of each other with respect to the force F ′, it is possible to create an optimum condition for the processing target. it can.

Referring again to FIG. 1, when the workpiece 8 is above the tool 7 (the workpiece 8
2), the reaction force F applied to the tool 7 is downward (the direction opposite to that in FIG. 2). Even in this case, the rotational moment Mo and the deflection angle θ are opposite to those in FIG. However, the floating unit according to the present invention functions similarly, although it receives a force F that pushes the intersection 3 downward.

[0026]

As described above, in the floating unit according to the present invention, the tool holder is fixed to the intersecting body of the two beams made of the elastic body. Since the beam of the book absorbs the force by bending, the degree of freedom of the movable range of the tool holder is increased, so that no excessive force is applied to the tool and therefore the tool is not damaged, and the work piece is processed. Since it is not necessary to change the processing conditions by changing the inclination of the surface, it is not necessary to teach the robot the movement of the robot arm in response to the processing direction.

Further, if the two beams are orthogonal to each other, the force in the pressing direction and the force in the working direction can correspond to each other independently, so that the working conditions can be easily created. it can.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram (perspective view) of a floating unit according to an embodiment of the present invention.

FIG. 2 is a schematic diagram when a floating unit according to an embodiment of the present invention is pressed downward.

FIG. 3 is a schematic diagram when a floating unit according to an embodiment of the present invention is pressed in a direction perpendicular to the paper surface.

FIG. 4 is a conceptual configuration diagram of a floating unit according to a conventional technique.

[Explanation of symbols]

 1 Floating unit main body according to the present invention 2 Beam composed of elastic body according to the present invention 2A One beam composed of elastic body according to the present invention 2B Other beam composed of elastic body according to the present invention 3 Beam Intersection According to the Invention 4 Ball Bearing 5 Stopper 6 Tool Holder 7 Tool 8 Workpiece 9 Robot Arm 10 Floating Rotation Center According to Prior Art 11 Stopper According to Prior Art 12 Compression Spring According to Prior Art 13 Compression According to Prior Art Spring fulcrum F Force in the pressing direction applied to the tool F'Force in the processing direction applied to the tool f Force applied to the tool holder according to the conventional technology l Beam length ls Vertical distance from the beam intersection to the processing point lr Beam Horizontal distance from the intersection point to the processing point lf Floating amount θ Deflection angle of beam 2A θ ′ Deflection angle of beam 2B

Claims (1)

[Claims] 1. A box-shaped floating unit main body (1) fixed to a robot arm (9) and rotatably fixed inside the floating unit main body (1) so as to intersect with each other and intersect ( 3) is fixed to each other, and two rigid beams (2) made of an elastic body, and a rigid tool holder (which extends from the intersection (3) from a surface formed by the two beams (2)). 6) A floating unit comprising: