Robot Hand

Abstract

To provide a robot hand, a workpiece conveyance device, and a workpiece conveyance program which can appropriately bring a suction part into contact with a workpiece.SOLUTION: A hand part 20 is used in a workpiece conveyance device 10 which sucks, suspends and conveys a workpiece W that is a bag body storing liquid, powder or a granule. The hand part 20 includes: a suction pad 25 having a suction surface 25a which generates a negative pressure and sucks a surface of the workpiece W; a connection part 24 connected to the workpiece conveyance device 10; and a floating mechanism 80 which is arranged between the connection part 24 and the suction pad 25, and makes the suction surface 25a of the suction pad 25 follow the surface of the workpiece W.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention is a robotic handle. Do It is related to. [Background technology]

[0002] Conventionally, palletizing robots and handling robots have been used to automate the depalletizing work (or palletizing work, the same applies hereinafter) of bags and the like. A robot hand used for automating such depalletizing work is known, for example, from Patent Document 1.

[0003] The robot hand described in Patent Document 1 brings a suction pad into contact with the workpiece to be depalletized, and then applies vacuum suction force to the suction pad via the chamber to which it is connected, thereby suctioning and lifting the workpiece with the suction pad, and transporting it in this lifted state.

[0004] Workpieces, such as bags containing rice or grains, are intangible and easily deformed. Therefore, when stacked on a pallet, errors in the loading and unloading position during palletizing (stacking) or vibrations during transport can cause the load to collapse inward or break and collapse outward. In other words, not all of the workpieces may be stacked evenly. If the robot hand's position cannot be controlled so that the suction pads contact the center of the workpiece, the workpiece W will be lifted by eccentric suction at a location that is off-center. If the magnitude of the moment generated by the misalignment exceeds the suction force of the suction pads, the workpiece may come off the suction pads and fall during depalletizing.

[0005] Therefore, the robot hand in Patent Document 2 is provided with a moment detection means that detects the moment generated by the eccentricity of the workpiece held by the suction pad, and a control unit that changes the suction pad's suction position on the workpiece based on the moment detected by the moment detection means, thereby enabling the suction pad to reliably suction the center of gravity of the workpiece. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-80370 [Patent Document 2] Japanese Patent Application Publication No. 9-262786 Summary of the Invention [Problem to be solved by the invention]

[0007] However, not only do bags and other workpieces become misaligned, but their top surfaces may not be horizontal. That is, bags containing rice, grains, and other such products may change shape due to the movement of the contents, causing the top surface to tilt relative to the horizontal.

[0008] In this case, even if the suction pad is pressed vertically downward against the workpiece, a gap occurs because the upper surface of the workpiece is inclined, reducing the suction force and making it impossible to suction stably.

[0009] The present invention has been made in view of the above-mentioned problems, and its object is to provide a robot handle that can appropriately bring a suction part into contact with a workpiece even when the workpiece has a variation in posture. Do The purpose is to provide. [Means for solving the problem]

[0010] To solve the above problems 1st The robot hand is A robot hand used in a workpiece transport device that adsorbs a workpiece that is a bag containing a liquid, powder, or granular material, lifts it, and transports the workpiece, a suction unit having a suction surface that generates negative pressure and suctions the surface of the workpiece; a connection portion connected to the workpiece transport device; a floating mechanism that is disposed between the connection portion and the suction portion and causes the suction surface of the suction portion to follow the surface of the workpiece. 、 The floating mechanism includes: a first plate fixed to the connection portion; a second plate to which the adsorption portion is fixed and which faces the first plate; a shaft provided upright on the second plate; an elastic body disposed between the first plate and the second plate and applying an elastic force in a direction in which the first plate and the second plate move apart, the first plate has a tapered hole whose diameter decreases toward the second plate; a tapered portion having a tapered surface corresponding to the shape of the tapered hole is provided at the tip of the shaft; the shaft is configured to be able to be inserted into and removed from the tapered hole and to be able to swing, and the tapered portion is configured to be housed in the tapered hole and be able to be locked to the tapered hole, The outer diameter of the shaft is configured to be smaller than the diameter of the small diameter portion of the tapered hole, the tapered hole is provided to penetrate the first plate, and an opening of the tapered hole on the connection portion side is closed by the connection portion; The vertical length dimension of the tapered hole is formed to be longer than the vertical length dimension of the tapered portion, and the size of the large diameter portion of the tapered hole is formed to be larger than the size of the large diameter portion of the tapered portion, so that a clearance is provided between the tapered portion and the connection portion when the tapered portion is engaged with the tapered hole. The second robot hand for solving the above problem is: A robot hand used in a workpiece transport device that adsorbs a workpiece that is a bag containing a liquid, powder, or granular material, lifts it, and transports the workpiece, a suction unit having a suction surface that generates negative pressure and suctions the surface of the workpiece; a connection portion connected to the workpiece transport device; a floating mechanism disposed between the connection portion and the suction portion, which causes a suction surface of the suction portion to follow the surface of the workpiece; The floating mechanism includes: a first plate fixed to the connection portion; a second plate to which the adsorption portion is fixed and which faces the first plate; a shaft provided upright on the second plate; an elastic body disposed between the first plate and the second plate and applying an elastic force in a direction in which the first plate and the second plate move apart, the first plate has a tapered hole whose diameter decreases toward the second plate; a tapered portion having a tapered surface corresponding to the shape of the tapered hole is provided at the tip of the shaft; the shaft is configured to be able to be inserted into and removed from the tapered hole and to be able to swing, and the tapered portion is configured to be housed in the tapered hole and be able to be locked to the tapered hole, The outer diameter of the shaft is configured to be smaller than the diameter of the small diameter portion of the tapered hole, a vertical length dimension of the tapered hole is longer than a vertical length dimension of the tapered portion, and a size of a large diameter portion of the tapered hole is larger than a size of the large diameter portion of the tapered portion, the elastic body is a coil spring attached to the outside of the shaft, and a second spring support for the coil spring is provided at least on the end of each end of the coil spring that is closer to the second plate; the second spring bearing portion has a second cylindrical portion through which the shaft is inserted and a second flange portion provided on an outer periphery of the second cylindrical portion, an end of the coil spring on the second plate side is attached to the outside of the second cylindrical portion and is in pressure contact with the second plate via the second flange portion; The outer diameter of the second cylindrical portion is larger than the diameter of the small diameter portion of the tapered hole, a first spring support for the coil spring is provided at an end of each of both ends of the coil spring that is closer to the first plate; an end portion of the coil spring on the first plate side is attached to the outside of a first cylindrical portion of the first spring receiving portion on the first plate side and abuts against the first plate via a first flange portion provided on an outer periphery of the first cylindrical portion; The inner diameter of the first spring bearing portion on the first plate side is formed larger than the diameter of the shaft, The first spring bearing portion on the first plate side is in slidable contact with the first plate.

[0011] This allows the suction portion to be brought into proper contact with the surface of the workpiece, enabling stable suction even when the workpiece has varying postures. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. [Figure 2] FIG. 1 is a perspective view of a robot hand seen from above. [Figure 3] FIG. 1 is a perspective view of a robot hand seen from below. [Figure 4] Front view of the robot hand. [Figure 5] Side view of a robotic hand. [Figure 6] FIG. [Figure 7] Cross-sectional view of the floating mechanism taken along line AA. [Figure 8] FIG. 4 is a partial cross-sectional view showing the operation of the hand portion. [Figure 9] FIG. [Figure 10] FIG. 4 is a partial cross-sectional view showing the operation of the hand portion. [Figure 11] FIG. 10 is a cross-sectional view of a floating mechanism according to a modified example. [Figure 12] FIG. 10 is a block diagram showing the configuration of a control device in a second embodiment. [Figure 13] 10 is a flowchart of a transport process according to a second embodiment. [Figure 14] FIG. 10 is a partial cross-sectional view showing an operation mode of a hand portion in the second embodiment. [Figure 15] FIG. 10 is a partial cross-sectional view showing an operation mode of a hand portion in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the "robot hand" according to the present invention will be described with reference to the drawings. In the following embodiments and modifications, identical or equivalent parts are denoted by the same reference numerals in the drawings, and the explanations of the parts with the same reference numerals are incorporated herein by reference. In addition to the combinations of the configurations explicitly shown in the description of the embodiments and modifications, it is also possible to combine the embodiments and modifications as long as there is no particular problem with the combination.

[0018] (First embodiment) As shown in Fig. 1, the workpiece transport device 10 is a device that sequentially transports workpieces W from a supply location and aligns and loads them on a portable pallet P installed at a predetermined position, i.e., a device that performs palletizing. Note that the workpiece transport device 10 is also a device that sequentially transports the workpieces W that have been aligned and loaded on a portable pallet P installed at a predetermined position to a predetermined discharge location, i.e., a device that performs depalletizing. When depalletizing, basically, the operations when palletizing are performed are reversed, and therefore, in this embodiment, palletizing will be mainly described.

[0019] As shown in Fig. 10, the workpiece W is a bag containing rice, grains, etc. The object contained in the bag may be a liquid, a powder, or a granular material, such as a granular plastic raw material or flour.

[0020] The workpiece W is supplied from an external conveying facility (such as a belt conveyor) to a roller conveyor 1 provided in the workpiece conveying device 10. The supplied workpiece W is then positioned and stopped at a predetermined rest position by a stopper (not shown) provided on the roller conveyor 1. The workpiece conveying device 10 is configured to detect the workpiece W positioned and stopped on the roller conveyor 1 with a sensor or the like, and then lift and convey it.

[0021] When depalletizing is performed, the reverse operation of the palletizing described above is performed. That is, the workpieces W are lifted from the pallet P by the workpiece transport device 10 and discharged to external transport equipment via the roller conveyor 1 or the like.

[0022] Next, the configuration of the workpiece transportation device 10 will be described in detail. As shown in Fig. 1, the workpiece transportation device 10 includes a hand unit 20 as a robot hand that grips the workpiece W, a transportation mechanism 30 that moves the hand unit 20, and a rectangular parallelepiped frame 70 to which the transportation mechanism 30 is fixed. The workpiece transportation device 10 also includes a control device 100 that controls the operations of the hand unit 20 and the transportation mechanism 30, and a controller (not shown) that serves as an information terminal that can input and output various types of information.

[0023] In this embodiment, the longitudinal direction of the frame 70 is the X-axis direction, the lateral direction (the direction perpendicular to the X-axis) is the Y-axis direction, and the direction perpendicular to the X-axis and Y-axis directions is the Z-axis direction. Note that, since the workpiece transport device 10 is usually installed on a flat surface, the Z-axis direction corresponds to the up-down direction (vertical direction). Furthermore, the X-axis direction and the Y-axis direction correspond to the horizontal direction.

[0024] The transport mechanism 30 has a pillar portion 50 fixed to a frame body 70 and formed to extend along the Z-axis direction, and an arm portion 60 fixed to the pillar portion 50 and formed to extend along the Y-axis direction.

[0025] An X-axis guide rail 51 is provided on the frame body 70 along the X-axis direction, and the pillar portion 50 is fixed to the X-axis guide rail 51 so as to be movable along the X-axis direction. The pillar portion 50 is drivingly connected to the output shaft of an X-axis servo motor 91 disposed at the bottom of the frame body 70 via a toothed belt or the like. In other words, the pillar portion 50 is configured to move back and forth in the X-axis direction along the X-axis guide rail 51 based on the driving force of the X-axis servo motor 91.

[0026] A Z-axis guide rail 61 is provided on the pillar 50 along the Z-axis direction, and the arm 60 is fixed to the Z-axis guide rail 61 so as to be movable along the Z-axis direction. The arm 60 is drivingly connected to the output shaft of a Z-axis servo motor 93 provided on the pillar 50 via a toothed belt or the like. In other words, the arm 60 is configured to move back and forth in the Z-axis direction along the Z-axis guide rail 61 based on the driving force of the Z-axis servo motor 93.

[0027] A Y-axis guide rail 21 is provided on the arm unit 60 along the Y-axis direction, and the hand unit 20 is fixed to the Y-axis guide rail 21 so as to be movable along the Y-axis direction. The hand unit 20 is drivingly connected to the output shaft of a Y-axis servo motor 92 provided on the arm unit 60 via a toothed belt or the like. In other words, the hand unit 20 is configured to move back and forth in the Y-axis direction along the Y-axis guide rail 21 based on the driving force of the Y-axis servo motor 92.

[0028] As described above, the transport mechanism 30 is configured to be able to linearly move the hand unit 20 in two directions (X-axis direction and Y-axis direction) that are orthogonal to the horizontal direction, and in the vertical direction (Z-axis direction).

[0029] 1, the hand unit 20 is fixed to the arm unit 60 via a rotation mechanism 23 serving as a rotation unit. The rotation mechanism 23 is configured to be able to rotate the hand unit 20 around the Z axis (in the direction of arrow R in FIG. 1) with the rotation mechanism 23 as the center based on the driving force of a built-in rotation axis servo motor 94.

[0030] As shown in Figures 2 and 3, the hand unit 20 has a connection part 24 that is connected to and fixed to the rotation mechanism 23, a suction pad 25 as a suction part, and a floating mechanism 80 that is arranged between the connection part 24 and the suction pad 25. The suction pad 25 is provided with its suction surface 25a facing downward. An ejector is connected to the suction pad 25 via an air pipe (not shown). Operation of the ejector creates a negative pressure inside the suction pad 25, which makes it possible to suction the upper surface of the workpiece W. The contact part of the suction pad 25 is made of rubber or sponge and is configured to absorb unevenness on the surface of the workpiece W to some extent.

[0031] The floating mechanism 80 is for causing the suction surface 25a of the suction pad 25 to follow the surface (the upper surface in this embodiment) of the workpiece W, and will be described in detail later.

[0032] Next, the control device 100 will be described. The control device 100 is an electronic control device equipped with a well-known microcomputer including a CPU, ROM, RAM, flash memory, etc. The control device 100 is equipped with drive circuits for driving the various servo motors 91 to 94 described above, and is configured to be able to control the operation of the various servo motors 91 to 94 via the drive circuits.

[0033] The control device 100 is connected to various sensors, various servo motors 91-94, a controller, etc., and is configured to be able to acquire various types of information. The control device 100 also has various functions and executes the various functions based on the acquired information. These functions are realized by executing programs stored in a storage device (storage memory) included in the control device 100. The various functions may be realized by electronic circuits, which are hardware, or at least a portion of them may be realized by software, i.e., by processing executed on a computer.

[0034] Among the various functions, there is, for example, a palletizing function that transports the workpieces W and loads them on a pallet P. Briefly explaining the palletizing function, the control device 100 detects the position of the workpieces W using a sensor or the like, lifts the workpieces W with the hand unit 20, moves the hand unit 20 together with the workpieces W onto the pallet P using the transport mechanism 30, and releases them, thereby loading the workpieces W. With this function, the workpieces W are stacked in multiple stages in the vertical direction (Z-axis direction) on the pallet P. At this time, the workpieces W may be stacked in multiple rows in a predetermined direction (X-axis direction or Y-axis direction) on each stage.

[0035] The various functions may include, for example, a depalletizing function that transports the workpieces W loaded on the pallet P one by one. Briefly explaining the depalletizing function, it is a function that detects the position of each workpiece W loaded on the pallet P using a sensor or the like, lifts the workpiece W whose position has been detected using the hand unit 20, and transports it from the pallet P to a predetermined discharge location.

[0036] As described above, the workpiece W in this embodiment is a bag containing rice, grains, or the like. Therefore, although the bag maintains the shape of the workpiece W to some extent, the shape may change due to the movement of the contents, and the top surface may be inclined relative to the horizontal plane. In this case, with a conventional robot hand, even if a suction pad is pressed against the workpiece W so that it is perpendicular to the horizontal, a gap may occur because the top surface of the workpiece W is inclined, reducing the suction force and making it impossible to stably suction the workpiece W.

[0037] In the hand unit 20 of this embodiment, a floating mechanism 80 is provided between the connection part 24 and the suction pad 25, which causes the suction surface 25a of the suction pad 25 to follow the surface (the upper surface in this embodiment) of the workpiece W. The floating mechanism 80 will be described in detail below with reference to FIGS. 2 to 7.

[0038] As shown in Figures 2 and 4, the floating mechanism 80 comprises a first plate 81 fixed to the connection portion 24, a second plate 82 to which the suction pad 25 is fixed and which faces the first plate 81 (in the vertical direction in Figure 4), shafts 83a to 83c which are arranged upright on the second plate 82, and a coil spring 84 as an elastic body which is arranged between the first plate 81 and the second plate 82 and applies an elastic force in the direction in which they move apart.

[0039] The first plate 81 is configured in a disk shape as shown in Fig. 6. As shown in Fig. 2 and Fig. 4, the first plate 81 is disposed above the hand unit 20 in the vertical direction (Z-axis direction), and the connection unit 24 is attached to the upper surface thereof.

[0040] 7, the first plate 81 has tapered holes 81a to 81c that penetrate the first plate 81 in the vertical direction in FIG. 7. The tapered holes 81a to 81c have tapered surfaces that decrease in diameter toward the second plate 82 (i.e., downward). The inclination angle α (the elevation angle with respect to the horizontal direction, see FIG. 7) of the tapered surfaces of the tapered holes 81a to 81c is set within a range of 45 to 60 degrees, and is set to 45 degrees in this embodiment. As shown in FIG. 6, the tapered holes 81a to 81c are provided in three locations, and are arranged so that the distance between the centers of the tapered holes 81a to 81c is equal. In other words, the tapered holes 81a to 81c are arranged so that the centers of the tapered holes 81a to 81c are located at the vertices of an equilateral triangle.

[0041] 2 and other figures, the second plate 82 is configured in the shape of a long plate, and is disposed below the first plate 81 in the vertical direction, facing the first plate 81 in the vertical direction. The suction pad 25 is fixed to the lower surface of the second plate 82, and the shafts 83a to 83c are erected on the upper surface of the second plate 82.

[0042] 2 and 6, three shafts 83a to 83c are provided and are arranged at positions corresponding to the tapered holes 81a to 81c of the first plate 81. That is, the shafts 83a to 83c are arranged so that the distance between the centers thereof is equal to the distance between the centers of the tapered holes 81a to 81c. In other words, the shafts 83a to 83c are arranged so that the central axes of the shafts 83a to 83c are located at the vertices of an equilateral triangle.

[0043] 4 and 7, the shafts 83a to 83c are each formed in a rod shape and are fixed so as to be perpendicular to the upper surface of the second plate 82. In other words, when the second plate 82 is disposed opposite to the first plate 81, the shafts 83a to 83c are shaped to extend from the second plate 82 toward the first plate 81. The tips of the shafts 83a to 83c (the ends opposite the second plate 82) are inserted into the tapered holes 81a to 81c of the first plate 81.

[0044] 7, the tips of the shafts 83a to 83c inserted into the tapered holes 81a to 81c are provided with tapered sections 85, which are generally truncated cones and have tapered surfaces that correspond to the shapes of the tapered holes 81a to 81c. The tapered sections 85 are housed inside the tapered holes 81a to 81c and are provided so as to be able to be locked into the tapered holes 81a to 81c.

[0045] More specifically, the tapered portion 85 is formed so that its diameter decreases toward the second plate 82, i.e., so that its diameter increases as it moves away from the second plate 82. The outer diameter of the small-diameter portion (lower portion) of the tapered portion 85 is equal to or larger than the diameter R3 of the small-diameter portion of the tapered holes 81a to 81c. In this embodiment, the outer diameter of the small-diameter portion of the tapered portion 85 is set to be slightly larger than the diameter R3 of the small-diameter portion of the tapered holes 81a to 81c. The outer diameter R2 of the large-diameter portion (upper portion) of the tapered portion 85 is formed to be larger than at least the diameter R3 of the small-diameter portion of the tapered holes 81a to 81c. Therefore, the tapered portion 85 is locked by the tapered holes 81a to 81c.

[0046] Furthermore, as described above, since the tapered portion 85 has a tapered surface that corresponds to the shape of the tapered holes 81a to 81c, the inclination angle α of the tapered surface of the tapered portion 85 is the same as the inclination angle α of the tapered surfaces of the tapered holes 81a to 81c. That is, in this embodiment, the inclination angle α of the tapered surface of the tapered portion 85 is 45 degrees. Therefore, as shown in FIG. 7, when the shafts 83a to 83c are oriented in the vertical direction, the tapered portion 85 comes into surface contact with the tapered holes 81a to 81c. Therefore, when the tapered portion 85 is engaged with the tapered holes 81a to 81c, it is stably engaged.

[0047] Furthermore, the vertical length dimension L1 of the tapered portion 85 is shorter than the vertical length dimension L2 of the tapered holes 81a to 81c, and in this embodiment, is approximately half the length dimension. Furthermore, the outer diameter R2 of the large diameter portion of the tapered portion 85 is configured to be smaller than the diameter R4 of the large diameter portion of the tapered holes 81a to 81c. In other words, when the tapered portion 85 is engaged with the tapered holes 81a to 81c, a gap (clearance) is provided above the tapered portion 85. Therefore, the shafts 83a to 83c are configured to be movable in the vertical direction relative to the first plate 81 and to be able to move in and out of the tapered holes 81a to 81c.

[0048] 7, the diameter R1 of the shafts 83a to 83c is smaller than the diameter R3 of the small diameter portions of the tapered holes 81a to 81c. Specifically, the diameter R1 of the shafts 83a to 83c is about half the diameter R3 of the small diameter portions of the tapered holes 81a to 81c. The tapered portions 85 attached to the tips of the shafts 83a to 83c are housed in the tapered holes 81a to 81c, which have diameters that increase with increasing distance from the second plate 82.

[0049] As a result of the above, when the tapered portion 85 is pressed toward the first plate 81 (the side opposite to the second plate 82), the shafts 83a to 83c are able to move a predetermined distance in the horizontal direction. In addition, as shown in Fig. 9, when the tapered portion 85 is pressed toward the first plate 81, the shafts 83a to 83c are able to tilt at a predetermined angle (indicated by angle β in Fig. 9). In other words, when the tapered portion 85 is pressed toward the first plate 81, the shafts 83a to 83c are configured to be able to swing relative to the first plate 81.

[0050] Next, the coil spring 84 will be described. As shown in Fig. 2 and Fig. 7, the coil spring 84 is a compression coil spring disposed between the first plate 81 and the second plate 82, and applies elastic force in the direction in which they move apart. The coil spring 84 is attached to the outside of each of the shafts 83a to 83c. In other words, the shafts 83a to 83c are disposed inside the coil spring 84.

[0051] As shown in FIG. 7, a spring receiving portion 86 for the coil spring is provided at one of both end portions of the coil spring 84 on the side of the second plate 82. The spring receiving portion 86 has a cylindrical portion 87 and a flange portion 88 provided on the outer periphery of the cylindrical portion 87. The shafts 83a to 83c are inserted inside the cylindrical portion 87. The cylindrical portion 87 moves along the shafts 83a to 83c. The end of the coil spring 84 on the side of the second plate 82 is attached to the outside of the cylindrical portion 87 and abuts (presses against) the second plate 82 via the flange portion 88. The outer diameter of the cylindrical portion 87 is approximately the same as the inner diameter of the coil spring 84. This prevents the end of the coil spring 84 from shifting laterally (i.e., outward) relative to the cylindrical portion 87.

[0052] The outer diameter of the flange 88 is formed to be larger than that of the coil spring 84. As a result, the coil spring 84 exerts an elastic force on the second plate 82 via the flange 88 of the spring receiving portion 86. At this time, the end of the coil spring 84 is prevented from shifting laterally relative to the cylindrical portion 87, and therefore applies an elastic force in the direction in which the shafts 83a to 83c extend, i.e., in the direction perpendicular to the second plate 82.

[0053] On the other hand, of both ends of the coil spring 84, at least the end closest to the first plate 81 is in direct contact with the first plate 81 and exerts an elastic force directly on the first plate 81. At this time, the coil spring 84 exerts an elastic force along the extension direction of the shafts 83a to 83c, but as described above, the shafts 83a to 83c are tiltable with respect to the first plate 81. As shown in FIGS. 8 and 9, when the shafts 83a to 83c are tilted with respect to the first plate 81, the distance between the first plate 81 and the second plate 82 is shortened, and therefore the elastic force of the coil spring 84 also increases. As a result, the tapered portions 85 engage with the tapered holes 81a to 81c, and the coil spring 84 exerts an elastic force such that the first plate 81 and the second plate 82 are parallel to each other.

[0054] The inner diameter of the coil spring 84 is larger than the diameter of the small-diameter portions of the tapered holes 81a-81c. The end of the coil spring 84 on the second plate 82 side is prevented from shifting laterally relative to the shafts 83a-83c by the spring receiving portion 86, and therefore the end of the coil spring 84 on the first plate 81 side is also prevented from shifting laterally much relative to the shafts 83a-83c. For this reason, even if the shafts 83a-83c are tilted relative to the first plate 81, as shown in Fig. 9, the coil spring 84 is prevented from entering the tapered holes 81a-81c.

[0055] Next, the operation of the floating mechanism 80 when the workpiece W is lifted by the hand unit 20 will be described with reference to FIGS. 8 to 10. Note that the description will be given assuming that the top surface of the workpiece W to be transported is inclined relative to the horizontal. Also, FIGS. 8 to 10 show the floating mechanism 80 in cross section. For convenience of explanation, the suction pads 25 are shown in simplified form, and the connection parts 24 are not shown.

[0056] After detecting the workpiece W, the control device 100 moves the hand unit 20 downward in the vertical direction (Z-axis direction) to press the suction surface 25a of the suction pad 25 against the workpiece W. That is, the suction surface 25a in a horizontal state is pressed against the upper surface of the workpiece W, which is inclined relative to the horizontal direction.

[0057] At this time, depending on the posture of the workpiece W, as shown in Figures 8 and 9, some or all of the shafts 83a to 83c are pressed into the tapered holes 81a to 81c of the first plate 81. Note that because the elastic force of the coil spring 84 is exerted in the direction separating the first plate 81 and the second plate 82, even if some of the shafts 83a to 83c are pressed in, not all of the shafts 83a to 83c are pressed in the same way. As a result, the shafts 83a to 83c are inclined relative to the first plate 81, and the second plate 82 is inclined. Accordingly, the suction surface 25a of the suction pad 25 to which the second plate 82 is fixed is inclined in accordance with the upper surface of the workpiece W. In other words, the suction surface 25a follows the upper surface of the workpiece W and abuts against it without any gaps.

[0058] After the contact, the control device 100 generates a negative pressure to cause the suction pads 25 to suction the workpiece W. After suction, the control device 100 moves the hand unit 20 upward. As shown in FIG. 10, when the hand unit 20 is moved upward, the weight of the workpiece W and the elastic force of the coil spring 84 cause the shafts 83a to 83c to be pulled out of the tapered holes 81a to 81c until the tapered portions 85 are engaged in the tapered holes 81a to 81c. When the shafts 83a to 83c are pulled out and the tapered portions 85 are engaged in the tapered holes 81a to 81c, the second plate 82 becomes horizontal, and the workpiece W being lifted also becomes horizontal.

[0059] The control device 100 moves the hand unit 20 upward, and then moves it horizontally. At this time, the tapered portion 85 comes into surface contact with the tapered holes 81a to 81c, so even if the workpiece W is moved horizontally, vibration is suppressed and the workpiece W is kept horizontal. This makes it possible to move the workpiece W stably horizontally.

[0060] According to the above embodiment, the following effects can be obtained.

[0061] A floating mechanism 80 is provided between the connection part 24 and the suction pad 25, which allows the suction surface 25a of the suction pad 25 to follow the surface of the workpiece W. This allows the suction pad 25 to be properly abutted against the surface of the workpiece W and to stably adsorb the workpiece W even if the posture of the workpiece W varies.

[0062] The shafts 83a to 83c are configured to be able to move in and out of the tapered holes 81a to 81c and to be swingable, and are equipped with coil springs 84 that apply elastic force in a direction that moves the first plate 81 and the second plate 82 away from each other. As a result, when the hand unit 20 is moved downward and the suction pad 25 is pressed against the workpiece W, some or all of the shafts 83a to 83c can be pressed into the tapered holes 81a to 81c depending on the inclination of the surface of the workpiece W. This allows the suction surface 25a of the suction pad 25 to be tilted in accordance with the top surface of the workpiece W. Note that because the elastic force of the coil springs 84 is exerted in a direction that moves the first plate 81 and the second plate 82 away from each other, even if some of the shafts 83a to 83c are pressed in, all of the shafts 83a to 83c will not be pressed in the same way, and the shafts can be tilted appropriately in accordance with the top surface of the workpiece W.

[0063] Furthermore, tapered portions 85 having tapered surfaces corresponding to the shapes of the tapered holes 81a to 81c are provided at the tips of the shafts 83a to 83c and are housed in the tapered holes 81a to 81c. As a result, when the hand unit 20 is moved upward after the workpiece W has been attracted, the tapered portions 85 are engaged with the tapered holes 81a to 81c by the weight of the workpiece W and the elastic force of the coil spring 84, and the second plate 82 and the workpiece W can be placed in a horizontal state. Therefore, the workpiece W can be moved horizontally in a stable state. When the tapered portions 85 are engaged with the tapered holes 81a to 81c, they come into surface contact, thereby suppressing vibration and maintaining a stable state.

[0064] The vertical length dimension L2 of the tapered holes 81a-81c is longer than the vertical length dimension L1 of the tapered portion 85, and the size (diameter R4) of the large diameter portion of the tapered holes 81a-81c is larger than the size (outer diameter R2) of the large diameter portion of the tapered portion 85. This allows the tapered portion 85 to move into the gap within the tapered holes 81a-81c by pushing the shafts 83a-83c into the tapered holes 81a-81c. At this time, the tapered portion 85 can be moved in the horizontal direction within the range of the tapered holes 81a-81c. As a result, the shafts 83a-83c can be swung relative to the first plate 81.

[0065] Furthermore, since the diameter R1 of the shafts 83a to 83c is smaller than the diameter R3 of the small diameter portion of the tapered holes 81a to 81c, there is a margin before the shafts 83a to 83c come into contact with the tapered holes 81a to 81c, and the tiltable angle of the shafts 83a to 83c can be increased.

[0066] Of both ends of the coil spring 84, the end closest to the second plate 82 is provided with a spring receiving portion 86 for the coil spring. The outer diameter of a cylindrical portion 87 of the coil spring 84 is set to be approximately the same as the inner diameter of the coil spring 84, so that the end of the coil spring 84 does not shift laterally relative to the cylindrical portion 87. This makes it possible to prevent the end of the coil spring 84 on the first plate 81 side from shifting laterally relative to the shafts 83a to 83c. Therefore, even if the shafts 83a to 83c are tilted relative to the first plate 81, the coil spring 84 can be prevented from entering the tapered holes 81a to 81c.

[0067] Three shafts 83a to 83c are provided and are not arranged in a straight line, which makes it easy to tilt the second plate 82 in the rotation direction about the X axis and the rotation direction about the Y axis.

[0068] Three shafts 83a to 83c are provided and are arranged so that the distance between each of the shafts 83a to 83c is equal. This allows for a larger inclination angle compared to when four or more shafts 83a to 83c are provided. In addition, all of the shafts 83a to 83c are arranged so as to fit within the surface area of ​​the workpiece W. This allows for a larger inclination angle while still reducing the size.

[0069] (Variation) A modified example in which the floating mechanism 80 in the above embodiment is partially modified will be described below.

[0070] In the above embodiment, as shown in FIG. 11 , a spring receiving portion 101 for the coil spring may be provided on one of both end portions of the coil spring 84 that is closer to the first plate 81. Similar to the spring receiving portion 86, this spring receiving portion 101 has a cylindrical portion 102 and a flange portion 103 provided on the outer periphery of the cylindrical portion 102. The shafts 83 a to 83 c are inserted inside the cylindrical portion 102. However, the inner diameter R3 of the cylindrical portion 102 is larger than the inner diameter of the cylindrical portion 87 of the spring receiving portion 86 on the second plate 82 side. The inner diameter R10 of the cylindrical portion 102 is configured to be sufficiently larger than the diameter R1 of the shafts 83 a to 83 c. Therefore, a gap is provided between the cylindrical portion 102 to allow the shafts 83 a to 83 c to move laterally.

[0071] 11(b), when the shafts 83a to 83c are pressed into the tapered holes 81a to 81c, the shafts 83a to 83c can tilt with respect to the cylindrical portion 102. In other words, the spring receiving portion 101 does not interfere with the tilting of the shafts 83a to 83c.

[0072] The outer diameter of spring receiving portion 101 is substantially the same as that of spring receiving portion 86. This allows coil spring 84 to exert elastic force on first plate 81 via flange 103 of spring receiving portion 101. Furthermore, the outer diameter of flange 103 is configured to be larger than the outer diameters of the small diameter portions of tapered holes 81a to 81c, which reliably prevents coil spring 84 from entering tapered holes 81a to 81c.

[0073] Furthermore, spring bearing portion 101 on the first plate side is in slidable contact with first plate 81. In other words, spring bearing portion 101 is configured to be slidable in the direction of arrow T in Fig. 11. Therefore, when shaft 83 is tilted, spring bearing portion 101 slides, eliminating interference with cylindrical portion 102 of spring bearing portion 101, allowing the tilt angle to be increased.

[0074] In the above embodiment, as shown in FIG. 11, the inclination angle of the tapered surfaces of the tapered holes 81a to 81c and the tapered portion 85 may be changed to 60 degrees.

[0075] In the above embodiment, the number and arrangement of the shafts 83a to 83c and the tapered holes 81a to 81c may be changed as desired.

[0076] (Second embodiment) A second embodiment, which is a partial modification of the first embodiment, will be described. In the second embodiment, the mechanical configuration of the workpiece transportation device 10 is the same as that of the first embodiment, so the same reference numerals are used and the description will be omitted. In the second embodiment, the processing contents and control contents by the control device 100 will be mainly described.

[0077] As shown in FIG. 12, the control device 100 is connected to various servo motors 91-94 and an ejector 95. The control device 100 controls the drive of the various servo motors 91-94, thereby moving the hand unit 20 along the X-axis, Y-axis, or Z-axis direction, and rotating (rotating) the hand unit 20 around a rotation axis (rotation axis). Therefore, in this embodiment, the control device 100 functions as a drive control unit. In addition, in this embodiment, the Z-axis servo motor 93 constitutes a first drive unit that moves the hand unit 20 in the vertical direction. In addition, the X-axis servo motor 91, the Y-axis servo motor 92, and the rotation axis servo motor 94 constitute a second drive unit that moves or rotates the hand unit 20 in the horizontal direction.

[0078] Furthermore, the control device 100 controls the operation of the ejector 95, thereby enabling the suction pad 25 to suction the upper surface of the workpiece W or to release the suction. Although not shown, the control device 100 is connected to various sensors, and grasps the position of the workpiece W based on the detection results from the various sensors, and controls the driving of the various servo motors 91 to 94 and the operation of the ejector 95.

[0079] Next, a description will be given of the processing contents of the control device 100 when the workpiece W is lifted by the hand unit 20. The control device 100 performs the transfer processing shown in Fig. 13 by executing a workpiece transfer program 97 stored in a storage device 96 provided in the control device 100. The transfer processing will be described in detail below.

[0080] When the transfer process is performed, the control device 100 confirms the position of the workpiece W to be transferred from the detection results of various sensors, and moves the hand unit 20 horizontally so that the hand unit 20 is positioned above the workpiece W (step S101). More specifically, in step S101, the control device 100 drives and controls the X-axis servo motor 91 to move the hand unit 20 in the X-axis direction so that the positions of the workpiece W and the hand unit 20 coincide with each other in the X-axis direction. The control device 100 also drives and controls the Y-axis servo motor 92 to move the hand unit 20 in the Y-axis direction so that the positions of the workpiece W and the hand unit 20 coincide with each other in the Y-axis direction. The control device 100 also drives and controls the pivot axis servo motor 94 to rotate the hand unit 20 so that the longitudinal direction of the hand unit 20 coincides with the longitudinal direction of the workpiece W.

[0081] Next, the control device 100 drives and controls the Z-axis servo motor 93 so as to lower the hand unit 20 toward the workpiece W (step S102). Then, the control device 100 sets a servo free state (free state) in which no torque is generated in any horizontal direction for the hand unit 20 when the suction surface 25a of the suction pad 25 is brought into contact with the surface of the workpiece W (step S103). Specifically, the control device 100 sets the servo free state so that no torque is generated in the horizontal direction by cutting off current to the X-axis servo motor 91 (X-axis motor), the Y-axis servo motor 92 (Y-axis motor), and the pivot axis servo motor 94 (rotation axis motor). Step S103 in this embodiment corresponds to a free control step.

[0082] The servo-free state may be a state in which the hand unit 20 (more specifically, the portion on the first plate 81 side) can move or rotate freely in the horizontal direction by an external force without being restricted in its horizontal movement or rotation by the torque of the servo motors 91, 92, and 94. Therefore, if no torque is being generated, it is not necessary to interrupt the current to the servo motors 91, 92, and 94.

[0083] Furthermore, the timing for setting the servo-free state, i.e., the start timing of step S103, may be any timing from when the hand unit 20 starts to descend (i.e., after the start of step S102) until before the suction surface 25a of the suction pad 25 comes into contact with the surface of the workpiece W. For example, a distance measuring sensor may be used to measure the distance between the hand unit 20 and the workpiece W, and the servo-free state may be set when the measured distance is equal to or less than a predetermined distance. Alternatively, the servo-free state may be set after a predetermined time has elapsed since the start of descent. Alternatively, the servo-free state may be set immediately after the start of descent.

[0084] The control device 100 controls the operation of the ejector 95 to adsorb the workpiece W after bringing the suction surface 25a of the suction pad 25 into contact with the surface of the workpiece W (step S104). After adsorption, the control device 100 controls the drive of the Z-axis servo motor 93 to raise the hand unit 20 that has adsorbed the workpiece W (step S105). After raising the hand unit 20 that has adsorbed the workpiece W, the control device 100 releases the servo-free state (step S106). The timing for releasing the servo-free state may be any timing from when the hand unit 20 starts to rise after the suction unit has adsorbed the workpiece to when the hand unit 20 completes the rise and moves or rotates in the horizontal direction. For example, the servo-free state may be released after a predetermined time has elapsed since the start of the rise to prevent the hand unit 20 from moving or rotating in the horizontal direction.

[0085] After the lift is complete, the control device 100 moves the hand unit 20 horizontally to a predetermined position (on the pallet P or to the destination on the roller conveyor 1) (step S107). That is, the control device 100 drives and controls the X-axis servo motor 91, etc., to move the hand unit 20. After moving the hand unit 20 to the predetermined position, the control device 100 lowers the hand unit 20, releases suction, and completes the transport of the workpiece W (step S108). Then, the transport process ends.

[0086] The effect of setting the servo-free state will be described with reference to Figures 14 and 15. Note that the explanation will be given assuming that the top surface of the workpiece W to be transported shown in Figures 14 and 15 is more inclined than the top surface of the workpiece W shown in Figure 8. Also, Figures 14 to 15 show the floating mechanism 80 in cross section. For convenience of explanation, the suction pads 25 are shown in a simplified form, and the connection portions 24 are not shown.

[0087] After detecting the workpiece W, the control device 100 lowers the hand unit 20 and presses the suction surface 25a of the suction pad 25 against the workpiece W. At this time, depending on the posture of the workpiece W, as shown in Fig. 14, some or all of the shafts 83a to 83c are pressed into the tapered holes 81a to 81c of the first plate 81. Note that because the elastic force of the coil spring 84 is exerted in a direction that separates the first plate 81 and the second plate 82, even if some of the shafts 83a to 83c are pressed in, all of the shafts 83a to 83c are not pressed in the same way.

[0088] As a result, the shafts 83a to 83c are inclined relative to the first plate 81, and the second plate 82 is inclined. When the shafts 83a to 83c are inclined to a certain extent, the tapered portions 85 come into contact with the inclined surfaces of the tapered holes 81a to 81c, or the shafts 83a to 83c come into contact with the small diameter portions of the tapered holes 81a to 81c.

[0089] At this time, in the first embodiment described above, the horizontal movement and rotation of the hand portion 20, more specifically the portion on the side of the first plate 81, was restricted by the torque of the servo motors 91, 92, and 94, so that the shafts 83a to 83c engaged with the tapered holes 81a to 81c and did not tilt any further.

[0090] However, in the second embodiment, a servo-free state is set for each of the servo motors 91, 92, and 94. Therefore, when the shafts 83a to 83c are tilted to a certain extent, the portions on the first plate 81 side move horizontally as shown by the arrows in Fig. 15 due to interference with the tapered holes 81a to 81c or the elastic force of the coil spring 84. This allows the shafts 83a to 83c to tilt further.

[0091] Accordingly, the second plate 82 and the suction pad 25 fixed thereto are also inclined further relative to the first plate 81. Therefore, the suction surface 25a can be made to more closely follow the inclination of the upper surface of the workpiece W and come into contact with it without any gaps.

[0092] According to the second embodiment, the following effects can be obtained.

[0093] When the control device 100 lowers the hand unit 20 and brings the suction surface 25a into contact with the surface (top surface) of the workpiece W, it sets a servo-free state in which no torque is generated in the horizontal direction for the hand unit 20. This allows the tilt angle to be increased in the floating mechanism 80. Therefore, the suction surface 25a can be made to more closely follow the tilt of the top surface of the workpiece W and come into contact with it without any gaps.

[0094] The control device 100 sets the servo-free state by cutting off the current to the servo motors 91, 92, and 94 when the suction surface 25a is brought into contact with the top surface of the workpiece W. This allows the servo-free state to be set with simple control and low power consumption. Furthermore, because movement in the X-axis and Y-axis directions and rotation are permitted, the top surface of the workpiece W can be moved in any orientation.

[0095] The control device 100 sets the servo-free state before the suction surface 25a is brought into contact with the upper surface of the workpiece W. After the suction pad 25 has adsorbed the workpiece W, the control device 100 releases the servo-free state. Therefore, when the shafts 83a to 83c tilt, the portions on the first plate 81 side can be reliably made movable without being hindered by the torque of the servo motors 91, 92, and 94.

[0096] The shafts 83a to 83c are configured to be able to move in and out of the tapered holes 81a to 81c, to be able to swing, and are equipped with coil springs 84 that apply elastic force in the direction in which the first plate 81 and the second plate 82 move apart. Therefore, when the inclination angle of the top surface of the workpiece W is large, the elastic force of the coil springs 84 allows the portion on the first plate 81 side to slide smoothly, making it possible to easily incline the shafts 83a to 83c.

[0097] Furthermore, by setting the servo-free state and configuring the floating mechanism 80, the suction surface 25a is tilted so as to follow the top surface of the workpiece W. Therefore, no power is consumed for tilting, and no special control is required.

[0098] The transfer process by the control device 100 and the workpiece transfer program 97 described in the second embodiment may be applied in combination with the first embodiment or the modified example.

[0099] In the second embodiment, the X-axis servo motor 91, the Y-axis servo motor 92, and the rotation axis servo motor 94 are all set to the servo free state, but it is also possible to set the servo free state for only one of them. In other words, it is also possible to set a servo free state in which no torque is generated in any of the horizontal directions. [Explanation of symbols]

[0100] 10...workpiece transport device, 20...hand portion, 24...connection portion, 25...suction pad, 25a...suction surface, 80...floating mechanism, 81...first plate, 81a to 81c...tapered hole, 82...second plate, 83a to 83c...shaft, 84...coil spring, 85...tapered portion, 86...spring support portion, 91...X-axis servo motor, 92...Y-axis servo motor, 93...Z-axis servo motor, 94...swivel axis servo motor, 95...ejector, 96...storage device, 97...workpiece transport program, 100...control device, W...workpiece.

Claims

1. A robot hand used in a workpiece transport device that adsorbs a workpiece that is a bag containing a liquid, powder, or granular material, lifts it, and transports the workpiece, a suction unit having a suction surface that generates negative pressure and suctions the surface of the workpiece; a connection portion connected to the workpiece transport device; a floating mechanism disposed between the connection portion and the suction portion, which causes a suction surface of the suction portion to follow the surface of the workpiece; The floating mechanism includes: a first plate fixed to the connection portion; a second plate to which the suction portion is fixed and which faces the first plate; a shaft provided upright on the second plate; an elastic body disposed between the first plate and the second plate and applying an elastic force in a direction in which the first plate and the second plate are separated from each other; the first plate has a tapered hole whose diameter decreases toward the second plate; a tapered portion having a tapered surface corresponding to the shape of the tapered hole is provided at the tip of the shaft; the shaft is configured to be able to be inserted into and removed from the tapered hole and to be able to swing, and the tapered portion is configured to be housed in the tapered hole and be able to be locked to the tapered hole, The outer diameter of the shaft is configured to be smaller than the diameter of the small diameter portion of the tapered hole, the tapered hole is provided to penetrate the first plate, the first plate is fixed to the connection portion such that an opening of the tapered hole on the connection portion side is covered by the connection portion from above, The vertical length dimension of the tapered hole is formed to be longer than the vertical length dimension of the tapered portion, and the size of the large diameter portion of the tapered hole is formed to be larger than the size of the large diameter portion of the tapered portion, thereby providing a clearance between the tapered portion and the connection portion when the tapered portion is engaged with the tapered hole.

2. the elastic body is a coil spring attached to the outside of the shaft, and a second spring support (86) for the coil spring is provided at least on the end of the coil spring that is on the second plate side, The second spring bearing portion has a second cylindrical portion (87) through which the shaft is inserted and a second flange portion (88) provided on the outer periphery of the second cylindrical portion, an end of the coil spring on the second plate side is attached to the outside of the second cylindrical portion and is in pressure contact with the second plate via the second flange portion; The robot hand according to claim 1 , wherein the outer diameter of the second cylindrical portion is larger than the diameter of the small diameter portion of the tapered hole.

3. A first spring support (101) for the coil spring is provided at the end of each end of the coil spring that is closer to the first plate, an end portion of the coil spring on the first plate side is attached to the outside of a first cylindrical portion (102) of the first spring receiving portion on the first plate side, and abuts against the first plate via a first flange portion (103) provided on the outer periphery of the first cylindrical portion; The robot hand according to claim 2 , wherein an inner diameter of the first spring bearing portion on the first plate side is formed larger than a diameter of the shaft.

4. The robot hand according to claim 3 , wherein the first spring bearing portion on the first plate side is in slidable contact with the first plate.

5. A robot hand used in a workpiece transport device that adsorbs a workpiece that is a bag containing a liquid, powder, or granular material, lifts it, and transports the workpiece, a suction unit having a suction surface that generates negative pressure and suctions the surface of the workpiece; a connection portion connected to the workpiece transport device; a floating mechanism disposed between the connection portion and the suction portion, which causes a suction surface of the suction portion to follow the surface of the workpiece; The floating mechanism includes: a first plate fixed to the connection portion; a second plate to which the suction portion is fixed and which faces the first plate; a shaft provided upright on the second plate; an elastic body disposed between the first plate and the second plate and applying an elastic force in a direction in which the first plate and the second plate are separated from each other; the first plate has a tapered hole whose diameter decreases toward the second plate; a tapered portion having a tapered surface corresponding to the shape of the tapered hole is provided at the tip of the shaft; the shaft is configured to be able to be inserted into and removed from the tapered hole and to be able to swing, and the tapered portion is configured to be housed in the tapered hole and be able to be locked to the tapered hole, The outer diameter of the shaft is configured to be smaller than the diameter of the small diameter portion of the tapered hole, a vertical length dimension of the tapered hole is longer than a vertical length dimension of the tapered portion, and a size of a large diameter portion of the tapered hole is larger than a size of the large diameter portion of the tapered portion, the elastic body is a coil spring attached to the outside of the shaft, and a second spring support (86) for the coil spring is provided at least on the end of the coil spring that is on the second plate side, The second spring bearing portion has a second cylindrical portion (87) through which the shaft is inserted and a second flange portion (88) provided on the outer periphery of the second cylindrical portion, an end of the coil spring on the second plate side is attached to the outside of the second cylindrical portion and is in pressure contact with the second plate via the second flange portion; The outer diameter of the second cylindrical portion is larger than the diameter of the small diameter portion of the tapered hole, A first spring support (101) for the coil spring is provided at the end of each end of the coil spring that is closer to the first plate, an end portion of the coil spring on the first plate side is attached to the outside of a first cylindrical portion (102) of the first spring receiving portion on the first plate side, and abuts against the first plate via a first flange portion (103) provided on the outer periphery of the first cylindrical portion; The inner diameter of the first spring bearing portion on the first plate side is formed larger than the diameter of the shaft, The first spring receiving portion on the first plate side is in slidable contact with the first plate.

6. The robot hand according to any one of claims 1 to 5, wherein three or more of the shafts are provided and are not arranged in a straight line.

7. The robot hand according to any one of claims 1 to 5, wherein three shafts are provided, the shafts are arranged so that the distance between each shaft is equal, and all the shafts are arranged so that they fit within the surface area of ​​the workpiece.

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