JP2009078312A - Articulated robot hand and articulated robot using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive articulated robot hand having improved working efficiency for efficiently gripping a workpiece having various attitudes in a predetermined attitude. <P>SOLUTION: A robot hand 1 is mounted on a Z-shaft 5 of an articulated robot 4 so as to be rotation-controllable around the vertical axis. It comprises a chuck mechanism 14 having a pair of opposed pawl pieces movable close to or apart from each other for gripping a workpiece, an oscillating mechanism 15 for giving oscillating motion to the chuck mechanism 14 downward within a predetermined angle, a rotating mechanism for giving positive/reverse rotation to the chuck mechanism 14 around a rotating shaft 12, and a control device for individually controlling the chuck mechanism 14, the oscillating mechanism 15 and the rotating mechanism. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-joint robot hand mounted on an output end of a multi-joint robot and a multi-joint robot provided with the hand.

  In the automatic assembly process of workpieces, since the workpieces that are carried into the automatic assembly step are usually in a stacked state, the postures of the workpieces carried on the work table vary. For this reason, in automatic assembly of workpieces, a robot that changes workpieces in various postures is important. In such a robot, a 6-axis robot has a function of capturing a workpiece with an image, recognizing it with a position and shape, and changing the workpiece based on the recognized information. However, the 6-axis robot is not only expensive, but also has a problem that it is difficult to grasp a small workpiece because the hand portion for grasping the workpiece is large.

  Further, in order to change the posture of the work carried on the work table to a predetermined posture, a horizontal articulated robot generally called SCARA is known. In this horizontal articulated robot, the Z-axis is held at the tip of an articulated arm that is movable in the horizontal direction, and an air chuck that grips the workpiece or a suction pad that attracts the workpiece is attached to the lower end of the Z-axis. The hand part provided with is provided.

  In the case of the robot hands of Patent Document 1 and Patent Document 2 below, an air cylinder that can be raised and lowered is attached to the tip of the robot arm, and a pair of flat plate portions extending in the vertical direction are provided at the lower end of the air cylinder. A component suction nozzle is provided between the pair of flat plate portions, and an air cylinder is provided between the pair of flat plate portions. The upper end of the component suction nozzle is coupled to the cylinder rod of the air cylinder via a link.

  In this robot hand, when the cylinder rod is extended, the component suction nozzle rotates diagonally through the link. When the lower end of the link hits a member such as a stopper, the cylinder rod stops extending and the tilt angle of the component suction nozzle Is fixed. Further, when the cylinder rod is contracted, the component suction nozzle starts to be directed in the vertical direction via the link, and finally the component suction nozzle is configured to be directed directly below the vertical direction.

In the one disclosed in Patent Document 2, a hand shaft that can be expanded and contracted in the Z-axis direction is attached to the scalar of Patent Document 1, and a hand support portion is screwed to the lower end portion of the hand shaft. The hand axis is rotatable around the Z axis. When the hand axis is contracted, the hand support is raised and restrained to the arm side so that it cannot rotate. When the hand axis is further rotated, the hand axis supports the hand. The height of the stopper that stops the link of the component suction nozzle can be adjusted via a pin that is screwed into the portion and penetrates the hand support portion.
JP-A-7-108482 JP-A-7-116984

  However, since conventional horizontal articulated robots are good at handling workpieces in a horizontal plane, they have a plurality of arms. If the shaft and joints are further increased in the hand part, there is a problem that it becomes expensive. In addition, even with a configuration that has an arm, a hand portion, etc. so that any posture can be changed, the posture of each workpiece varies, so the stroke of the cylinder rod of the air cylinder used for the Z-axis is different each time. Since the cylinder rod must be returned to a predetermined position in order to change the stroke, it is difficult to change the stroke quickly.

  Furthermore, in the case of what is disclosed in Patent Documents 1 and 2, the component suction nozzle is rotatably provided between the pair of flat plate portions provided at the lower end portion of the air cylinder, and is disposed between the pair of flat plate portions. Since the cylinder rod of the air cylinder is connected to the component suction nozzle via a link, the shape of the tip of the hand is large. For this reason, when approaching the workpiece to be grasped, there is a problem that the workpiece is moved in contact with the workpiece around the target workpiece, and it becomes difficult to grasp the workpiece by moving the target workpiece.

  Furthermore, even if the angle of the chuck at the tip can be changed to an arbitrary angle, if the adjustment of the arm of the horizontal articulated robot or the extension amount of the Z-axis and the change of the chuck angle is not performed, an arbitrary posture can be obtained. There is a problem that it is difficult to control the posture of the chuck according to the workpiece. That is, there is a problem that if the horizontal articulated robot does not have an emphasis operation with respect to the posture angle of the hand unit, a tilting operation or a complicated operation for gripping the workpiece or incorporating the workpiece cannot be performed.

  Also, in the work gripping work and the work assembly work, the posture of gripping the workpiece is basically the same, corrected in the horizontal plane, or limited to either horizontal or vertical posture, and the front and back are reversed. If the inclination is different and there is a difference in posture in the height direction or the vertical direction, the posture conversion of the workpiece is not free.

  In any case, since the postures of the workpieces arbitrarily scattered on the work table are various, when only a workpiece in a specific posture can be gripped, the workpiece conveyance efficiency is lowered. Further, if the circulation of the work is repeated on a belt conveyor or the like in order to take a specific posture with respect to the work, there is a problem that not only the cycle time becomes longer, but also the power consumption increases and the production efficiency deteriorates.

  The present invention has been made paying attention to the above-mentioned problems, and in automatic assembly and other work processes, it is possible to efficiently grasp a workpiece having various and unspecified postures in a predetermined posture, and it is inexpensive and efficient. An object of the present invention is to provide an articulated robot hand and an articulated robot.

  The articulated robot hand of the present invention is an articulated robot hand that is detachably attached to an output end of an articulated robot configured to be slidable in the vertical direction and rotatable about a vertical axis. A chuck mechanism for gripping a workpiece, a rotating mechanism for holding the chuck mechanism and rotating the chuck mechanism forward and backward about its central axis, and holding the rotating mechanism and detachably attached to the output end. And a swing mechanism that rotates the rotation mechanism within a predetermined angle range downward, and a control unit that individually controls the chuck mechanism, the rotation mechanism, and the swing mechanism.

  According to the above-described hand, the chuck mechanism that grips the workpiece can be rotated forward and backward around the central axis that supports the chuck itself by the rotation mechanism, and the rotation mechanism itself can be rotated from the output end of the Z-axis by the swing mechanism. Since the rotation mechanism and the swing mechanism are controlled by the control device, the chuck can be directed in various directions, and workpieces of various postures can be controlled by the control mechanism. It can be gripped.

  In the above articulated robot hand, the chuck mechanism may include a pair of claw pieces and a mirror operation type linear motor that simultaneously moves the pair of claw pieces in a detaching direction. good. When the pair of claw pieces is driven by a mirror operation type linear motor, the workpiece can be positioned and gripped at the center of the pair of claw pieces, so even if the chuck mechanism is moved to various angles, Since the workpiece is easy to position, it is easy to grip the workpiece. Further, when the multi-joint robot is provided with any of the above-mentioned hands, the workpiece control means and the control means of the multi-joint robot can grasp the workpieces in various postures according to the workpiece postures. This can be easily performed and can be achieved with an inexpensive configuration.

  A multi-joint robot hand according to the best embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an articulated robot hand and an articulated robot according to an embodiment of the present invention. Reference numeral 1 denotes a robot hand. The robot hand 1 includes a hand base 2. A substantially cylindrical attachment portion 3 is attached to the upper end portion of the hand base 2. The attachment part 3 is detachably attached to the lower end part (the output end of the articulated robot) of the Z-axis 5 of the articulated robot 4. The Z-axis 5 is movable in the horizontal direction by the first arm 6 and the second arm 7 by a control device 50 (see FIG. 2) which is a control means of the articulated robot 4, and the vertical axis by the θ-axis 8. The rotation angle can be adjusted around. The Z axis 5 can be moved up and down in the vertical axis direction. In this embodiment, the control means of the robot hand 1 is constituted by a part of the control device 50 of the articulated robot. However, even if the robot hand 1 itself has a computer, a converter circuit and the like as the control means. good.

  The hand base 2 includes a cylindrical fixed portion 9 extending in the axial direction of the Z-axis 5, a movable portion 11 that is attached to the fixed portion 9 and that can control the rotation angle about a rotation shaft 10 (see FIG. 3), A pedestal portion 13 capable of controlling the rotation angle about the rotation axis 12 with respect to the movable portion 11, a mirror operation type chuck mechanism 14 provided on the pedestal portion 13, and a swing mechanism 15 are provided.

  FIG. 3 is a cross-sectional view showing the configuration of the multi-joint robot hand 1. As shown in FIG. 3, the fixing portion 9 includes an upper cylindrical portion 15 that fixes the output end of the Z-axis 5 by fastening bolts and nuts, and a lower cylindrical portion 16 that is fixed below the upper cylindrical portion 15. It has. A pair of bearing portions 17 facing each other are formed in the lower portion of the lower cylindrical portion 16.

  The swing mechanism 15 includes a pair of bearing portions 17 and 25, a rotating shaft 10, a geared motor 18, pulleys 19 and 24, and an endless belt 20. A geared motor 18 having a reduction gear, an AC servomotor, and a rotary encoder is attached to a side wall portion of the lower cylindrical portion 16. The rotation direction and the rotation angle of the geared motor 18 are controlled by a control device 50 (see FIG. 2) including a computer for controlling the articulated robot 4.

  A pulley 19 is fixed to the rotating shaft of the geared motor 18, and an endless belt 20 is stretched around the pulley 19. A movable part 11 is disposed between the pair of bearing parts 17. Each of the pair of bearing portions 17 is provided with a mounting hole for rotatably mounting the movable portion 11, and a ring outside the bearing 21 is mounted inside the mounting hole. A rotating shaft 10 is rotatably fixed in a ring inside the bearing 21.

  An end portion of the rotating shaft 10 positioned outside the bearing portion 17 is formed with a collar portion 22 for preventing the dropping, and a cylindrical portion 23 is attached to a portion positioned inside the bearing portion 17 of the rotating shaft 22. ing. Both the inner peripheral surface and the outer peripheral surface of the cylindrical portion 23 are formed so that keys that protrude outwardly from the outer peripheral surface of the cylindrical portion 23 and inside the inner peripheral surface of the cylindrical portion 23 extend in the axial direction. The cylinder portion 23 is configured to rotate integrally with the rotary shaft 22 and the movable portion 11. A pulley 24 is attached to the end portion on the further inner side of the one cylindrical portion 23 so as to be integral with the cylindrical portion 23 and non-rotatable. The endless belt 20 is stretched around the outer peripheral surface of the pulley 24.

  The movable portion 11 is formed with a pair of bearing portions 25 corresponding to the pair of bearing portions 17, and the cylindrical portion 23 is attached to the pair of bearing portions 25 so as not to be rotatable by a key and a key mechanism. . When the rotating shaft of the geared motor 18 rotates, the rotation of the pulley 19 is transmitted to the pulley 24 via the endless belt 20, and the rotational force of the pulley 24 is transmitted to the cylindrical portion 23 and the pair of bearing portions 25. The rotating shaft 10 is rotated as an axis. The rotation direction and rotation angle of the geared motor 18 are transmitted to the control device 50 of the articulated robot 4 via the rotary encoder, and the geared motor 18 rotates in a predetermined direction and angle based on the control command of the control device 50. Stop.

  A mounting plate 26 having a hole in the center is formed between the pair of bearing portions 25 of the movable portion 11, and a geared motor 27 is attached to the mounting plate 26. A rotating mechanism 30 that allows the chuck mechanism 14 to rotate forward and backward around the vertical axis is provided inside the movable portion 11. The rotation mechanism 30 includes a geared motor 27, a cylindrical portion 28, a bearing 29, and a hand mounting plate 31. The geared motor 27 includes an AC servo motor, a rotary encoder, and a reduction gear mechanism, and the rotation direction and the rotation angle are controlled by the control device 50 of the articulated robot described above. The rotating shaft 12 of the geared motor 27 protrudes downward from the hole of the mounting plate 26. Base portions of the pair of bearing portions 25 of the movable portion 11 are fixed to the cylindrical portion 28. A bearing 29 is attached to the outer peripheral surface of the cylindrical portion 28. A fixed frame 31 a is attached to the outside of the bearing 29. A hand attachment plate 31 is attached to the lower end of the fixed frame 31a.

  A cylindrical portion 32 is integrally formed on the upper surface portion of the hand mounting plate 31. The cylindrical portion 32 and the rotating shaft 12 of the geared motor 27 are mounted so as not to rotate with each other by a key and a keyway mechanism so that when the rotating shaft 12 rotates, the hand mounting plate 31 rotates integrally with the rotating shaft 12. It is configured.

  As shown in FIGS. 1 and 2, the chuck mechanism 14 includes a chuck base 33 that is fixed to the hand mounting plate 31 with a bolt or the like. A screw 35 that is rotated by a motor 34 is provided between opposite side wall portions of the chuck base 33, and a slide block 36 is screwed to the screw 35. The chuck base 33 is provided with a linear encoder 37 that outputs the moving direction and moving amount of the slide block 36 as detection signals. The slide block 36 is provided with a claw support portion 38, and a claw piece 39 is attached to the claw support portion 38.

  On both sides of the central portion of the screw 35, thread threads extending in opposite directions are formed by right and left screws. A slide block 36 is screwed to each of the right and left threads of the screw 35. A guide groove (not shown) extending along the screw 35 is formed on the chuck base 33 side, and the above-described slide blocks 36 are slidably mounted in the guide groove. The linear encoder 37 that detects the moving direction and the moving amount of the slide block 36 is provided on the chuck base 33 side, but may be provided on the slide block 36 side.

  The moving direction and moving amount of the slide block 36 detected by the linear encoder 37 are transmitted to the control device 50 of the articulated robot 4 described above. The control device 50 of the articulated robot 4 monitors the movement amount and direction of the linear encoder 37 and the movements of the first arm 6, the second arm 7, the Z axis 5, the θ axis 8, and the AC servo motor 18, The AC servomotor 18, the AC servomotor 27, and the linear motor 34 are driven and controlled so that the hand 1 performs a predetermined operation in accordance with these movements.

  FIG. 4 is a conceptual diagram showing a state when a workpiece is gripped by the articulated robot 4 using the articulated robot hand of this embodiment. In FIG. 4, the robot hand 1 is disposed above the belt conveyor 41 that conveys the workpiece 40, and stands by for gripping the workpiece 40. A CCD camera 42 for monitoring the posture of the workpiece 40 is provided above the belt conveyor 41 and upstream of the flow of conveying the workpiece 40. On the further upstream side of the belt conveyor 41, a feeder 43 for carrying the workpiece 40 onto the belt conveyor 41 is provided. Further, a belt conveyor 44 for returning the workpiece 40a that has not been gripped to the feeder 43 side is disposed downstream of the belt conveyor 41 in the conveying direction. The workpiece 40a dropped on the belt conveyor 44 from the belt conveyor 41 is conveyed to the belt conveyor 44 and is put into the opening 43a of the feeder 43 by an inclined belt conveyor (not shown). 44 and the feeder 43 are circulated.

  The CCD camera 42 monitors the workpiece 40 on the belt conveyor 41, and the photographed image of the CCD camera 42 is transmitted to the control device 50 of the articulated robot 4 described above. The control device 50 compares the captured image captured by the CCD camera 42 with the captured image of the workpiece 40 captured in advance. The control device 50 stores a photographed image regarding the posture of the workpiece 40 carried on the belt conveyor 41 and a direction in which the chuck mechanism 14 should face the posture of the workpiece 40 in the photographed image.

  Since the alignment between the CCD camera 42 and the work 40 on the belt conveyor 41 is substantially constant, the CCD camera 42 can take an image of the work 40 in focus when the work 40 on the belt conveyor 41 is taken. The control device 50 stores in advance a large number of postures that can be taken by the work 40 wound on the belt conveyor 41 as photographed images. For each photographed image, there are many postures when the workpiece 40 of the photographed image is gripped. The position where the Z axis 5 of the joint robot 4 should be and the direction in which the robot hand 1 should face are stored as a table. That is, the posture of the robot hand 1 when the workpiece 40 is gripped by the robot hand 1, the horizontal movement and vertical movement of the Z-axis 5 of the articulated robot 4, and the θ-axis angle are related to each other. The data is stored in the control device 50 in advance as a set of captured images of the work 40.

  Therefore, when the captured image of the work 40 is transmitted from the CCD camera 42, the control device 50 selects the captured image that is most similar to the captured image stored in advance and compares the captured image with the captured image. The Z-axis 5 of the articulated robot 4 is controlled so as to match the posture of the workpiece 40 in the image, the orientation of the robot hand 1 is controlled, and the chuck mechanism 14 is operated to grip the workpiece 40. At that time, based on the photographed image of the workpiece 40 photographed by the CCD camera 42, the horizontal position and the vertical position of the articulated robot 4 and the θ-axis rotation angle are approximated to the photographed image without being calculated. Since the stored image is selected and determined, and control is performed according to the operation of the articulated robot 4 and the operation of the robot hand 1 associated with the stored image, a quick gripping operation of the workpiece 40 can be performed.

  As described above, the multi-joint robot hand 1 of this embodiment is attached to the Z-axis 5 that is the output end of the multi-joint robot 4, and the Z-axis 5 moves in the horizontal direction and in the vertical direction. It is attached around 5 so that rotation control is possible. The movable portion 11 of the hand base 2 of the robot hand 1 is attached so that the rotation angle can be controlled in the direction around the axis with respect to the rotation axis 10 orthogonal to the vertical axis direction in which the Z axis 5 extends. Further, a pedestal portion 13 having a pair of claw pieces 39 is mounted so as to be rotatable in a direction around the axis of the rotation shaft 12 which is further orthogonal to the rotation shaft 10, and the pedestal portion 13 is opposed to each other by a motor 34. A chuck mechanism 14 having a pair of claw pieces 39 that can be separated and can grip a workpiece is provided.

  A geared motor 18 that swings the movable portion 11, a geared motor 27 that rotates the pedestal portion 13, and a motor 34 that opens and closes the pair of claw pieces 39 of the chuck mechanism 14 are controlled by the control device 50. The moving amount and moving direction of the geared motors 18 and 27 are controlled based on detection signals of rotary encoders provided in the geared motors 18 and 27. The motor 34 that opens and closes the chuck mechanism 14 is controlled by the control device 50 based on the detection signal of the linear encoder 37, and controls the opening / closing operation of the pair of claw pieces 39.

  According to the robot hand 1 described above, the control device 50 of the articulated robot 4 can adjust the rotation angle in the direction around the axes of the swing mechanism 15 and the rotation mechanism 30 in addition to the operation control of the articulated robot 4. Therefore, the chuck mechanism 14 can be directed in various directions. In addition, the workpiece 40 having various postures can be gripped by the pair of claw pieces 39 under the control of the linear motor 34.

  In the above articulated robot hand 1, the pair of claw pieces 39 is configured by a mirror operation type chuck that can be approached and separated symmetrically, so that the workpiece 40 is positioned at the center of the pair of claw pieces 39. Can be gripped. Thereby, even if the base part 13 is moved to various angles, it is easy to position the workpiece 40 between the pair of claw pieces 39 and to easily grip the workpiece 40. The control device 50 of the articulated robot 4 includes the robot hand 1 described above and can immediately determine the most appropriate orientation of the robot hand 1 from the image captured by the CCD camera 42. This can be quickly grasped according to the posture of the workpiece 40, and this can be achieved with an inexpensive configuration.

It is the schematic of the hand for articulated robots concerning embodiment of this invention. It is explanatory drawing of the state which rotated the movable part of the robot hand of FIG. 1 around the rotating shaft. It is the schematic which shows the structure of the hand base of the robot hand of FIG. 1, FIG. It is the schematic which shows the state which hold | grips a workpiece | work using the robot hand shown in FIG.

Explanation of symbols

  1: Robot hand, 2: Hand base, 4: Articulated robot, 5: Z-axis, 9: Fixed part, 10: Rotating axis, 11: Movable part, 12: Rotating axis, 13: Base part, 14: Chuck Mechanism: 15: Swing mechanism, 18: Geared motor, 27: Geared motor, 30: Rotating mechanism, 34: Linear motor, 39: Claw piece, 40: Workpiece, 50: Control device (control means for robot hand)

Claims (3)

An articulated robot hand that is detachably attached to an output end of an articulated robot configured to be slidable along the vertical direction and rotatable about a vertical axis,
A chuck mechanism for gripping the workpiece;
A rotating mechanism for holding the chuck mechanism and rotating the chuck mechanism forward and backward around its central axis;
A swing mechanism that holds the rotation mechanism and is detachably attached to the output end, and rotates the rotation mechanism within a predetermined angle range downward;
And a control means for individually controlling the chuck mechanism, the rotation mechanism, and the swing mechanism.   The articulated robot according to claim 1, wherein the chuck mechanism includes a pair of claw pieces and a mirror operation type linear motor that simultaneously moves the pair of claw pieces in a separation / contact direction. For hands.   An articulated robot comprising the articulated robot hand according to claim 1.

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