JPH05212644A - Tool positioning device - Google Patents

Abstract

PURPOSE:To provide a tool positioning device which is able to perform the positioning of a working tool primarily and compact in size and simple in mechanism. CONSTITUTION:Each center part 5a of holding surfaces 5 of three holding jaws (3a-3c) equally installed in the circumferential direction has a circular section of the same curvature with the circumscribed circle of a regular hexagonal section of a work object, 2 and its circular center angle is a circular curved surface of 60 deg. and this circular curved surface is centered at a centering point O at the maximum projecting end of the holding jaws (3a-3c) and it is set so as to accord with a circular arc of the same radius as the circumscribed circle of the work object 2. With this constitution, so far as this work object 2 is within the range of allowable maximum slippage, the holding surface 5 performs the centering motion surely owing to the intermittent drive of these holding jaws (3a-3c) even if it collides with a side face and the angle of a side face of the work object 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool positioning device, and more particularly, to a working tool provided at the tip of a compliant mechanism such as a manipulator.
The present invention relates to a device for precisely positioning an object provided on a plane so as to project upright in two directions on the plane.

[0002]

2. Description of the Related Art For example, a tool positioning device provided in a work robot for performing dangerous work such as handling radioactive materials or operating a nuclear reactor is used for a work object having a regular polygonal cross section such as a hexagon head. For precisely positioning the working tool provided at the tip of the manipulator. Specifically, a plurality of the working tools are arranged at equal intervals in the circumferential direction with respect to the centering center thereof. The gripping claw is provided, and the gripping claw is capable of projecting and retracting in the radial direction toward the centering center.

Then, the side surfaces of the bolt head provided so as to stand upright on the plane which is the centering surface are sandwiched by the plurality of gripping claws from the side, and the reaction tool at that time causes the working tool itself to be caught. Centering (positioning in two directions of the centering surface) is performed. In this case, the positional relationship around the axis of the hexagon bolt is not considered.

In the conventional positioning device, the gripping claws of the work tool have a flat gripping surface, and the number of gripping claws is the same as the number of corners of the regular polygonal cross section of the work object (the hexagonal shape described above). The number of bolts is 6), and these gripping claws are driven in synchronization.

[0005]

However, such a structure has the following problems, and its improvement has been demanded.

That is, since the gripping surface of the gripping claw is flat, if the side surface of the work object is sandwiched by this gripping surface,
The gripping state differs depending on whether the gripping surface is in contact with the side of the regular polygon or the apex of the cross-sectional shape of the work object, and the centering of the work tool cannot be uniquely performed.

For this reason, in order to perform precise positioning with respect to the work object, the operator needs to make adjustments while monitoring how the gripping claws hit the work object, which complicates the operation. Moreover, the mechanism becomes complicated and large-scaled.

Moreover, since it is necessary to drive a plurality of gripping claws in synchronization with each other, the mechanism is complicated and the scale is increased from this point as well.

The present invention has been made in view of the problems of the prior art, and it is an object of the present invention to provide a tool positioning device which can uniquely position a working tool and has a small mechanism and a simple mechanism. To aim.

[0010]

In the tool positioning device of the present invention, the working tools provided at the tip of the compliant mechanism are provided with a plurality of tools arranged at equal intervals in the circumferential direction with respect to the centering center thereof. The gripping claw is provided so that the gripping claw can project and retract in the radial direction toward the centering center, and the central portion of the gripping surface of the gripping claw is a circumscribed circle of a regular polygonal cross section of the work target. Is a circular curved surface having an arc-shaped cross section with the same curvature as, and the circular arc central angle of the circular curved surface of the gripping claw is set to 360 ° / n, where n is the number of regular polygonal cross-sections of the work object. At the maximum protruding end of the grip claw, the arc of the grip surface coincides with the arc of the center of the centering center and the radius of the circumscribed circle of the regular polygonal section. It is characterized in that is configured.

In the present invention, the plane piece width dimension of the gripping claw is such that when the allowable maximum deviation of the work object is l and the circumscribed circle radius of the regular polygonal cross section of the work object is R,
It is preferably set to l + R / 2.

Further, in the present invention, it is preferable that both end portions of the holding surface of the holding claw in the plane are flat surfaces extending in the tangential direction of the arc of the cross section at both ends of the center portion in the plane.

Furthermore, in the present invention, it is preferable that the gripping claws have a shape in which a portion of the gripping claws adjacent to each other that interferes with each other is cut out at the maximum protruding end thereof.

[0014]

By operating a plurality of gripping claws, these gripping claws move with respect to the work object with eccentricity, and as a result, the work object relatively moves toward the centering center of the working tool. Thus, the work tool is positioned with respect to the work target in two plane directions. In this case, the centering operation can be performed even if the gripping surface of the gripping claw hits the side surface of the work target or hits a corner.

That is, the central part of the grip surface of the grip claw is
A circular curved surface having an arcuate cross section having the same curvature as the circumscribed circle of the regular polygonal cross section of the work target is used, and the arc center angle of this circular curved face is the number n of the regular polygonal cross section of the work target. Is set to 360 ° / n. Furthermore, the moving stroke of the gripping claw, that is, the projecting / retracting stroke, at the maximum projecting end, the arc of the gripping surface is centered on the centering center and coincides with the arc having the same radius as the circumscribed circle of the regular polygonal section of the work object. Is set to.

Therefore, even if the position of the work tool with respect to the work object is initially deviated, the grasping pawl is intermittently (ON-OFF) as long as the work object is within the allowable maximum deviation amount that can be centered. When the gripping surface of the gripping claw hits the side surface of the work object or hits a corner, the centering operation can be performed by driving the gripping claws automatically, and automatic centering is surely performed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a main part of a tool positioning device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a working tool provided at the tip of a manipulator (not shown), and the manipulator is a mechanism having compliance. Reference numeral 2 denotes a hexagonal bolt head which is a work target, and the hexagonal bolt is provided so as to project upright on a plane which is a centering surface. Further, the hexagon bolt head 2 has a known regular hexagonal cross section.

The work tool 1 is provided with three gripping claws 3, ..., These gripping claws 3, ... Are equally spaced in the circumferential direction with respect to the center O of the centering, that is, are spaced 120 ° around the center O of the centering. It is located at. These grip claws 3,
2, each has a pneumatic cylinder 4 as a drive mechanism thereof, and the pneumatic cylinder 4
By driving the cylinder rod 4a, each of the gripping claws 3 is capable of projecting and retracting in the radial direction toward the center O of the centering.

All the gripping claws 3 have the same shape and size, and their design conditions are as follows (see FIGS. 2 to 4).

I. Inner surface of the gripping claw 3 that abuts on the work object (hexagonal bolt head) 2, that is, the central portion 5 of the gripping surface 5.
a is a circular curved surface having an arcuate cross section having the same curvature as the circumscribed circle Q (radius R) of the regular polygonal cross section of the work object 2.

II. The arc center angle α of the circular curved surface 5a of the grip claw 3 is set to 360 ° / n, where n is the number of corners of the regular polygonal cross section of the work object 2. Therefore, in the case of the illustrated example, since the work object 2 has a regular hexagonal cross section, the arc center angle α is set to 60 °.

III. The moving stroke of the grip claw 3, that is, the projecting / retracting stroke is set so that the maximum projecting end (stroke end) thereof is completely coincident with the circumscribed circle Q of the work object 2 when the centering is completed. ..

That is, at the stroke end of the cylinder rod 4a of the pneumatic cylinder 4, the circular arc of the circular curved surface 5a of the gripping surface 5 is an arc whose center is the center O and which has the same radius R as the circumscribed circle Q of the work object 2. The pneumatic cylinders 4 are arranged so as to overlap and coincide with each other.

The moving stroke (cylinder stroke) of the cylinder rod 4a of the pneumatic cylinder 4 is set to be the same as the maximum allowable deviation L of the work object 2 that can be centered.

IV. Both end portions 5 of the grip surface 5 of the grip claw 3
b and 5b are planes extending in the tangential direction of the curved arc at both ends of the circular curved surface 5a at the central portion. Therefore, in the case of the illustrated example, these both end portions 5
b and 5b are planes inclined at an angle of 60 ° with respect to the moving direction X of the grip claw 3 (the axial direction passing through the center of the circular curved surface).

V. The plane piece width dimension W of the grip claw 3 is set corresponding to the maximum allowable shift amount of the work target 2, and is represented by the following formula.

W = L + R / 2 where L: maximum allowable deviation of work object 2 R: radius of circumscribed circle of regular polygonal cross section of work object 2

VI. The gripping claw 3 has a shape in which the interfering portions of the adjacent gripping claws 3 are cut out at the maximum protruding end thereof.

That is, as shown in the figure, the grip claw 3 is long,
When the ends of adjacent gripping claws 3 interfere with each other at the maximum projecting end, that is, when centering is completed (see FIG. 1 (b)), notches 6 and 6 as shown in FIG. 3 are formed, respectively. ..

The notches 6 and 6 are formed by notching in the height direction (perpendicular to the centering surface) by a width that causes the gripping claws 3 to overlap each other. The width dimension from the axis X to the inner edge of the cutout portion 6 is set to be the same as the radius R of the circumscribing circle Q.

In the tool positioning device configured as described above, when the three gripping claws 3, ... Are driven by the pneumatic cylinders 4, ..., These gripping claws 3 ,. 2 (See Figure 1 (a))
Relative to the axis X direction, and as a result, the work object 2
Moves relative to the centering center O direction of the work tool 1 and the work tool 1 is positioned with respect to the work object 2 in the two plane directions (FIG. 1).
(See (b)).

In this case, the centering operation is surely performed even if the gripping surfaces 5, ... Of the gripping claws 3, ... Abut the side surface of the work object 2 or the corners. This point will be described below.

As shown in FIG. 4, consider a case where the centering center O of the work tool 1 and the center O'of the work object 2 are displaced from each other. At this time, one gripping claw 3a of the three gripping claws has one end apex A of its gripping surface 5 abutting on one side surface B of the work target 2, while the other gripping claw 3c is The grip surface 5 is a side surface vertex C of the work target 2.
Is in contact with.

First, regarding the gripping claw 3c, the gripping force does not work in the direction of pushing the work object 2 to the outside of the gripping surface 5 of the gripping claw 3c, so that centering is possible.

Next, the grip claw 3a will be considered. When the work object 2 is displaced by the allowable maximum displacement amount L,
The center O ′ is a radius L centered on the centering center O.
On the circumference of.

At this time, a line segment connecting the centering center O and the center O'of the work object 2 passes through the centering center O and is parallel to the end surface 5b of the gripping surface 5 (this line is the movement of the gripping claw 3c). The angle with (matching direction X) is β, and
The angle between the end surface 5b of the grip claw 3a and the one side surface B of the work target 2 is γ.

The condition that the gripping claw 3a does not let the work object 2 escape to the outside of the gripping surface 5, that is, the work object 2 can be centered in the centering center O direction is the direction of the pressing force (gripping force). To sin (30 ° -γ) ≧ 0
Therefore, γ ≦ 30 °.

Now, among the possible positions of the work object 2, γ is maximum when the center O'of the work object 2 is on the circumference of the radius L centered on the centering center O,
When β = 30 °, γ = 30 °.

Therefore, the work object 2 is always pushed relatively toward the centering center O (actually, the work tool 1 moves).

As described above, as long as the work object 2 is within the range of the maximum allowable deviation amount L that can be centered, the three gripping claws 3, ... Are intermittently (ON-OFF) driven to grip the object. Even if the grip surface 5 of the claw 3 hits the side surface of the work target 2 or hits a corner, the centering operation is possible, and automatic centering is surely performed. This eliminates the need for the operator to closely monitor and adjust the centering movement.

The present invention is not limited to the above-described embodiment, and various design changes can be made. In particular, I
As far as the design conditions of VI to VI are satisfied, the number of grip claws 3 and the number of corners of the regular polygonal cross section of the work object 2 can be changed as illustrated in FIGS. 5 to 7, and in any of these cases, The work object 2 can be centered and finally positioned uniquely.

That is, in FIG. 5, when the work object 2 has an equilateral triangular cross section and three grip claws 3 are used for this work object 2 (FIG. 5 (a)), the grip claw 3 is used. When using four grips (Fig. 5 (b)) and when using five gripping claws 3 (Fig. 5)
(c)) are shown respectively.

FIG. 6 shows that the work object 2 has a square cross section, and when three grip claws 3 are used for this work object 2 (FIG. 6 (a)), there are four grip claws 3. When used (Fig. 6
(b)) and the case where five gripping claws 3 are used (Fig. 6 (c)) are shown.

FIG. 7 shows that the work object 2 has a regular pentagonal cross section, and when three grip claws 3 are used for this work object 2 (FIG. 7 (a)), the grip claw 3 is set to four. When two are used (Fig. 7
7 (b)) and the case where five gripping claws 3 are used (FIG. 7 (c)).

Further, in order to drive the gripping claws 3, ..., In addition to the pneumatic cylinder 4 as shown in the drawing, other driving means utilizing hydraulic pressure, electric power or the like can be used.

[0047]

As described in detail above, according to the present invention,
Although the mechanism is simple, the working tool can be uniquely positioned. Further, since the mechanism is small and simple, its operation can be easily performed.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of a tool positioning device according to an embodiment of the present invention in relation to a hexagonal bolt head that is a work target, and FIG. Shows the state before the gripping claws of the work tool are positioned, (b)
Indicates the state of being positioned.

FIG. 2 is an enlarged plan view showing a drive mechanism portion of a grip claw in the positioning device.

FIG. 3 is an enlarged front view showing a grip claw in the positioning device.

FIG. 4 is an enlarged plan view for explaining design conditions of a shape and size of a grip claw in the positioning device.

FIG. 5 is a plan view showing a modified example of the gripping claws of the positioning device in relation to a work object having an equilateral triangular cross section, which is a work object, and (a) shows three gripping claws; Shows the case where there are four holding claws, and (c) shows the case where there are five holding claws.

FIG. 6 is a plan view showing a modified example of the gripping claws of the positioning device in relation to a work object having a square cross section, which is a work object. (A) shows three gripping claws; Shows the case where there are four holding claws, and (c) shows the case where there are five holding claws.

FIG. 7 is a plan view showing a modified example of the gripping claws of the positioning device in relation to a work object having a regular pentagonal cross section, which is a work object; (a) shows three gripping claws; Shows the case where there are four holding claws, and (c) shows the case where there are five holding claws.

[Explanation of symbols]

 1 Work Tool 2 Work Object 3 Gripping Claw 4 Pneumatic Cylinder 5 Gripping Claw Gripping Surface 5a Gripping Surface Center Part (Circular Curved Surface) 5b Gripping Surface Both Ends (Plane) O Centering Center O'Working Object Center Q Circumscribed circle of regular polygonal cross section of work target L Allowable maximum deviation of work target W Flat piece width dimension of gripping claw X Moving direction of gripping claw

Claims (4)

[Claims] 1. A work tool provided at the tip of a mechanism having compliance is mounted on a flat surface of a work object having a regular polygonal cross section, which is provided on the flat surface of the work tool.
A device for positioning in a direction, wherein the working tool includes a plurality of gripping pawls arranged at equal intervals in a circumferential direction with respect to a centering center thereof, and the gripping pawls radiate toward the centering center. The gripping claw has a circular curved surface having a circular arc-shaped cross section having the same curvature as the circumscribed circle of the regular polygonal cross section of the work target. The arc center angle of the circular curved surface is set to 360 ° / n, where n is the number of angles of the regular polygonal cross section of the work object, and the protrusion / retraction stroke of the gripping claw is at the maximum protrusion end. The tool positioning device is characterized in that the arc of the gripping surface is set so as to coincide with the arc centered on the centering center and having the same radius as the circumscribed circle of the regular polygonal cross section. 2. The plane piece width dimension of the gripping claw is l + R / 2, where l is the maximum allowable shift amount of the work object and R is the circumscribed circle radius of the regular polygonal cross section of the work object. The tool positioning device according to claim 1, which is set. 3. The flat end portions of the grip surface of the grip claw are
The tool positioning device according to claim 1, wherein the tool positioning device is a flat surface extending in a tangential direction of a circular arc of a cross section at both plane ends of the central portion. 4. The tool positioning device according to claim 1, wherein the gripping claw has a shape in which an interference portion between adjacent gripping claws is cut out at a maximum protruding end thereof.