JP2013185632A - Link mechanism transfer machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that a conventional machine has a structure made by merely combining a biaxial five-bar link and a parallel link, therefore, an available swingable angle range is restricted within about 90°, can be used only within a small range, is difficult to secure the accuracy of a trace and can not transfer to a predetermined position precisely while keeping a posture constant.SOLUTION: In a device which sets one first link of five-bar link mechanism, drives shafts of both ends thereof with a servo-motor and controls the position of a joint center opposite to the fixed bar, as an equivalent one to a parallelogram of a parallel link, in place of a lever attached to one side driving shaft 2, timing pulleys 8 having a length of the lever as radius are pivotally and concentrically attached, timing pulleys 8 of the same size are respectively pivotally attached to a joint shaft of the other end of the first link and a shaft of a working piece 5 and a timing belt 7 is stretched therein such that a straight line part gets to equal to a distance between axial centers and always forms a rectangular parallelogram.

Description

  The present invention controls a trajectory when an article to be transferred is moved between a plurality of appropriate points. For example, an object provided at the tip of a link mechanism attached to a frame of a transfer device. The present invention relates to a link mechanism transfer machine for transferring a gripping member for gripping the workpiece or transferring a tool for processing a small locus.

  2. Description of the Related Art Conventionally, a device attached to the wrist end of a robot, which is a first drive device fixed to a base of the device, a second drive device, and a first drive device directly connected to an output shaft of a speed reducer in the first drive device. And a second arm that is directly connected to the output shaft of the speed reducer in the second drive unit, and a five-bar linkage mechanism that links the two-axis arm and the tool with a link. There is a small trajectory processing device (see, for example, Patent Document 1) in which the lengths of the arms and links are set so that one of them enters the inside, and the trajectory of the tool is controlled.

Japanese Patent No. 2722295 (refer to claims, detailed description of the invention, and FIGS. 2 to 6)

However, the conventional link mechanism transfer machine has the following drawbacks.
Because it is a two-axis five-joint link structure, it is possible to move the head and workpiece while stabilizing the head and workpiece tip posture by attaching a parallel link, but the trajectory angle range used is about 90 degrees. Only a small range can be used, and if the large trajectory angle range is moved, the posture of the head and the work cannot be maintained, for example, the horizontal state cannot be maintained and it is tilted to ensure the accuracy of the trajectory. It is difficult, and it cannot be transferred to a predetermined position accurately and while maintaining a constant posture.
In other words, the five-bar link structure is folded inward and compactly stored, and because it is folded inward, the links on both sides of the tool are lined up in a straight line so that the tool cannot be moved. Since there is no point position, the overall structure of the drive unit can be made smaller compared to the case where the five-bar link structure projecting outwards always projects forward to avoid such a dead center state. . In addition, the 5-joint link structure folded inward does not allow the connecting part of the arm and the link to come out of the connecting point between the first or second driving device and the arm even during operation. It is designed so that it can be used with little interference even in narrow places standing on the wall.
On the other hand, the invention of the present application can use the trajectory angle range up to about 150 degrees, and when moving the article, it can be accurately transferred to a predetermined position and can be performed while keeping the posture constant. Is.

A first aspect of the present invention is a link mechanism transfer machine as set forth in claim 1 and is as follows.
The first link of the five-bar linkage mechanism, which is formed by sequentially connecting five links, is set as a fixed node, and the shafts at both ends are driven by servo motors to control the position of the joint center facing the fixed node. In the device, instead of the lever attached to one of the drive shafts, a timing pulley having the radius of the lever as a radius is pivotally attached in place of the lever attached to one of the drive shafts. Each of the other drive shaft and the operating piece shaft is pivotally attached, and the timing belt stretched here is configured so that the linear portion is equal to the distance between the shaft centers to always form a rectangular parallelogram.

Since the link mechanism transfer machine according to the present invention has the configuration as described above, the following effects can be obtained.
(1) The article transfer angle range can be set in a wider range than that of the conventional five-bar linkage mechanism.
(2) The locus position can be determined accurately.
(3) The posture of the mechanism tip can be kept constant.

It is a schematic explanatory drawing which shows the locus | trajectory state of the 5-joint link mechanism in the link mechanism transfer machine of this invention. It is a schematic explanatory drawing which shows the relationship between the 5 link mechanism of this invention, and an operating piece. It is a schematic explanatory drawing which shows the specific structure which provided the timing belt in the 5-joint link mechanism of this invention. It is a schematic explanatory drawing which shows the relationship between the 5-joint link mechanism which provided the timing belt in the 5-joint link mechanism of this invention, and an operation piece. In the link mechanism transfer machine of this invention, it is a schematic explanatory drawing which shows the state with which the timing belt was suspended with the drive pulley, the driven pulley, and each roller. It is a schematic explanatory drawing of one embodiment which shows the state which is performing the transfer transfer using the link mechanism transfer machine which has a 5-joint link mechanism of this invention. It is a schematic explanatory drawing which shows the state which stacks and reverses 90 degree | times using the link mechanism transfer machine which has a 5-joint link mechanism of this invention. The relationship between the concrete link mechanism of this invention and a timing belt is shown, (a) shows the state in which the driven pulley part is located in the downward substantially perpendicular | vertical direction, (b) shows a 90 degree timepiece of the driven pulley part. It is a schematic explanatory drawing which shows the state which moved around.

  The first link of the five-bar linkage mechanism, which is formed by sequentially connecting five links, is set as a fixed node, and the shafts at both ends are driven by servo motors to control the position of the joint center facing the fixed node. In the device, instead of the lever attached to one of the drive shafts, a timing pulley having the radius of the lever as a radius is pivotally attached in place of the lever attached to one of the drive shafts. A link mechanism that is pivotally attached to the other drive shaft and the shaft of the operating piece respectively, and the timing belt stretched here is made equal to the distance between the shaft centers so that a linear parallelogram is always formed. It is a transfer machine.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic explanatory view showing a trajectory state of a five-bar linkage mechanism showing the link mechanism transfer machine of the present invention, FIG. FIG. 4 is a schematic explanatory diagram showing a relationship between a five-bar link mechanism in which a timing belt is provided in a five-bar linkage mechanism and an operating piece. FIG. 5 is a schematic explanatory view showing a state in which the timing belt is suspended from the driving pulley, the driven pulley, and each roller in the link mechanism transfer machine.
As shown in FIG. 8, the link mechanism transfer machine of the present invention is a five-joint link mechanism in which five links are sequentially connected, and one first link is a fixed joint 1 and drive shafts at both ends thereof. 2 is driven by the first and second servo motors 3 and 4, and the position of the operating piece 5 attached to the drive shaft 2 is controlled by the third servo motor. 6 to control.
In FIG. 1, a link AB is a fixed node, and links BC and AD pivotally attached to this link swing around B and A as drive shafts, respectively. The links CP and DP are pivotally connected to the drive nodes BC and AD by C and D, and are pivotally connected to each other by the other end P.
As shown in FIG. 2, the operating piece 5 is pivotally attached to the point P, but only this determines the position of the point P as shown in the figure, but the posture cannot be determined. Therefore, in general, as shown in FIG. 2, the links A′D ′ and D ″ P ′, which are equal in length to the links AD and DP, are respectively connected to the short lever AA ′ and the small triangle DD′D ″. , And the lever PP ′ to provide two parallelograms. If the angle that the lever A′A makes with the horizontal direction is θ and the triangle ∠D′DD ″ is γ, the lever PP ′ always maintains an angle of θ−γ with respect to the horizontal direction. If the working piece 5 pivotally attached to the point P is connected to the lever PP ′, the posture of the working piece 5 can be kept constant.
The working piece 5 may be required to change its posture in accordance with the purpose during a driving cycle in order to provide functions such as workpiece adsorption, workpiece gripper, and mold. For this purpose, the object can be achieved by swinging the lever AA ′ with the third servo motor 6 about A as an axis.

The parallelogram is mechanically most stable when its internal angle is close to 90 degrees.
However, as can be understood from FIG. 2, the combination of the angle of the link constituting the five-bar link and the posture of the actuating piece 5 causes the parallelogram to become flat and the strength to receive the force cannot be maintained. is there. That is, there is a possibility that the stable operation by the five-bar link cannot be maintained.
The present invention is configured by replacing the posture control parallel link with a timing belt 7 and a timing pulley 8 as shown in FIGS.
Instead of the lever AA ′ attached to one drive shaft A, a timing pulley 8 having the radius of the lever AA ′ as a radius is pivotally connected, and the timing pulley 8 of the same dimension is connected to the axis D and the axis of the operating piece 5. Attaches to each P. The linear portion of the timing belt 7 stretched here is equal to the distance between the shaft centers, so that the swing angle α of the A-axis timing pulley 8 is equal to the swing angle of the operating piece 5 (see FIG. 2). Moreover, the parallelogram is equivalent to the link AD, DP and the radius of the timing belt 7 and the timing pulley 8 and always forms a rectangle, so that the timing belt 7 is stretched with a constant tension. For example, stable movement can be obtained regardless of the angle of the link.

Next, in order to oscillate these timing pulleys 8, a drive shaft of the timing pulley 8 is provided in the middle and upper M of the A axis and B axis, and is oscillated by the third servo motor 6. Since the distance between these axes is constant, the length of the straight portion of the timing belt 7 is also constant. A timing pulley 8 is provided below the M axis, and its axis is attached so that it can slide up and down. By adjusting the position of S, the tension of the timing belt 7 can be adjusted.
5 shows a state in which the timing belt 7 is suspended between the driving pulley and the driven pulley via the first to third free rollers and the five guide rollers, and the servo is changed from the state shown in FIG. It is driven by a motor to rotate in a circular arc, and the timing belt 7 is formed with a fixed length and is difficult to expand and contract. It is decided whether to draw a perfect trajectory.
FIG. 6 shows a case where it is applied to transfer transfer, and FIG. 7 shows a state where the stacked workpieces are inverted 90 degrees and the workpieces are transferred side by side. Is.

  It can also be used in a link mechanism transfer machine that is provided at the tip of the wrist of a robot, such as a workpiece suction, a workpiece gripper, or a gripper of a molding machine, and regulates the posture of the workpiece.

DESCRIPTION OF SYMBOLS 1 .... Fixed node 2 .... Drive shaft 3 .... First servo motor 4 .... Second servo motor 5 .... Operating piece 6 .... Third servo motor
7. Timing belt
8 ... Timing pulley AB ... Link BC ... Link AD ... Link CP ... Link DP ... Link A'D '... Link D'P '······· Link BC ··· Drive node AD ··· Drive node
P ··· Operating point AA '··· Short lever DD'D' ···· Small triangle PP '··· Lever

Claims (1)

The first link of the five-bar linkage mechanism, which is formed by sequentially connecting five links, is set as a fixed node, and the shafts at both ends are driven by servo motors to control the position of the joint center facing the fixed node. In the device, instead of the lever attached to one of the drive shafts, a timing pulley having the radius of the lever as a radius is pivotally attached in place of the lever attached to one of the drive shafts. The first link is pivotally attached to the joint shaft at the other end of the first link and the shaft of the operating piece, and the timing belt stretched on the first link is made equal to the distance between the shafts, and the rectangular parallelogram is always formed. A link mechanism transfer machine characterized in that it is formed.

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