Hand device

Abstract

A hand device according to the present disclosure comprises: a connection plate that is connected to the end of a robot arm; a hand base that can move toward and away from the connection plate; a pair of fingers that are supported by the hand base; an actuator that drives the opening and closing of the pair of fingers; and a biasing member that biases the pair of fingers in the distal direction thereof.

Description

Hand Device

[0001] The present disclosure relates to a hand device.

[0002] As robots become more sophisticated, the functions of the hands equipped on them are also becoming more sophisticated. For example, a hand capable of two types of operations, gripping a workpiece and pushing it into the workpiece, is known (see, for example, Patent Document 1). One method for performing these operations involves preparing two types of hands: a gripping hand and a pushing hand. However, this method incurs costs, installation space, and operating time due to hand changes. Another method involves providing a gripping mechanism and a pushing mechanism separately in the hand itself. However, this method increases the complexity of the hand, resulting in an overall larger size and weight. This makes it difficult to use the hand for gripping or pushing a workpiece, resulting in low versatility. Furthermore, the robot's posture must be changed to match the orientation of the gripping mechanism and the pushing mechanism, increasing the overall operating time. Another method involves preparing a pushing jig and having the gripping hand grip the pushing jig. However, when this method is adopted, costs increase due to the need to prepare a pushing jig, space must be secured for the pushing jig, and the operating time increases due to the need to hold the pushing jig in a hand.

[0003] Japanese Patent Application Laid-Open No. 2020-73297

[0004] It is desired to provide a hand device that can perform both the action of gripping a workpiece and the action of pushing the workpiece.

[0005] A hand device according to the present disclosure includes a hand base, a pair of fingers provided on the hand base, an actuator that drives the pair of fingers to open and close, and a biasing member that biases the pair of fingers toward their tips.

[0006] FIG. 1 is a diagram showing a robot arm mechanism equipped with a hand device according to this embodiment. FIG. 2 is a perspective view of the front portion of the hand device according to this embodiment, viewed obliquely from above. FIG. 3 is a perspective view of the front portion of the hand device of FIG. 2, viewed obliquely from below. FIG. 4 is a perspective view of the rear portion of the hand device of FIG. 2, viewed obliquely from above. FIG. 5 is a supplementary diagram for explaining the movement of a pair of fingers 94, 95 at the rear stage of the hand device according to this embodiment. FIG. 6 is a supplementary diagram for explaining the movement of two pairs of fingers of the hand device according to this embodiment. FIG. 7 is a diagram showing an example of a workpiece gripped by the hand device according to this embodiment. FIG. 8 is a supplementary diagram for explaining the workpiece pushing operation by the hand device according to this embodiment. FIG. 9 is a diagram showing an example of a workpiece pushed by the hand device according to this embodiment.

[0007] The hand device according to this embodiment will be described with reference to the drawings. In the following description, components having substantially the same functions and configurations are designated by the same reference numerals, and redundant description will be given only when necessary.

[0008] The hand device 2 according to this embodiment is configured to be able to perform both a workpiece gripping operation and a workpiece pushing operation. As shown in FIG. 1 , the hand device 2 can be used as an end effector for various types of robot arm mechanisms 1, such as a vertically articulated type, a horizontally articulated type, and a polar coordinate type. Of course, as long as the hand device 2 can be moved, it can be used not only in combination with the robot arm mechanism 1 but also in combination with various types of moving devices, such as an elevator that moves up and down along the vertical direction. The configuration of the hand device 2 will be described below with reference to FIGS. 2 to 4 . The hand coordinate system is defined as follows and will be used appropriately in the description. That is, the axis parallel to the direction in which the hand body 30 approaches and moves away from the connection plate 10 is the Z-axis, the axis parallel to the opening and closing direction of the pair of fingers 44, 45 (the pair of fingers 94, 95) is the X-axis, and the axis perpendicular to the X-axis and Z-axis is the Y-axis. The X-axis is also referred to as the left-right direction, the Y-axis is also referred to as the front-rear direction, and the Z-axis is also referred to as the up-down direction.

[0009] 2 to 4 , the hand device 2 includes a connection plate 10 connected to the tip of the robot arm mechanism 1, and a hand main body 30 provided so as to be able to move toward and away from the connection plate 10. The hand main body 30 includes a hand base 31, a pair of front fingers 44, 45 arranged in the front lower part of the hand base 31, a first actuator 40 that drives the opening and closing of the pair of front fingers 44, 45, a pair of rear fingers 94, 95 arranged in the rear lower part of the hand base 31, second and third actuators 50, 60 that drive the movement of the pair of rear fingers 94, 95 in the Y-axis direction, a second linear guide 25 that guides the movement of the pair of rear fingers 94, 95 in the Y-axis direction, and a transmission mechanism 70 that transmits power that opens and closes the pair of front fingers 44, 45 to the pair of rear fingers 94, 95.

[0010] The hand device 2 has a biasing member that biases the fingers 44, 45, 94, 95 toward their distal ends when the hand device 2 is not performing a pushing operation and is in a steady state with no load. In this embodiment, multiple compression springs 100 are interposed between the connection plate 10 and the hand base 31 as biasing members. The multiple compression springs 100 preferably have the same spring specifications, i.e., the same steady length and spring constant when unloaded. Note that this does not deny a structure in which a single compression spring 100 is provided. Nor does it deny the provision of multiple compression springs 100 with different spring specifications.

[0011] When the hand device 2 is in a steady state without a pushing operation and no load is applied, a compression spring 100 is interposed between the connection plate 10 and the hand body 30 in a slightly compressed state to urge fingers 44, 45, 94, and 95 (described below) toward their tips. To ensure that the compression spring 100 is in a slightly compressed state, a stopper 17 is provided to restrict the maximum distance of the hand body 30 (hand base 31) from the connection plate 10 so that it is shorter than the steady length of the compression spring 100. The stopper 17 is provided on the connection plate 10. The hand body 30 is guided by a first linear guide 20 to guide movement of the hand body 30 relative to the connection plate 10 in the Z-axis direction and to restrict movement in the X-axis and Y-axis directions. A first guide rail 21 constituting the first linear guide 20 is provided on the connection plate 10 in a direction parallel to the Z-axis, and a first guide block 22 movable along the first guide rail 21 is provided on the hand body 30 side.

[0012] The biasing member may be a rubber plate, a leaf spring, or other elastic member instead of a compression spring. The biasing member is not limited to the elastic member described above, and may be an air damper, a hydraulic damper, or other member.

[0013] The finger 44 has a finger body 46 made of metal and having the shape of an elongated rectangular prism. A resin plate-shaped claw portion 48 is attached to the outer surface of the finger body 46 on the tip side thereof so as to protrude from the tip of the finger body 46. The other fingers 45, 94, and 95 are configured in the same manner as the finger 44, and therefore a description thereof will be omitted.

[0014] The pair of fingers 44, 45 in the front stage are supported on the front side of the hand base 31 via a first actuator 40. The first actuator 40 has a linear first moving rail 41, a pair of first finger bases 42, 43 that are movable toward and away from each other along the first moving rail 41, and a motor (not shown) that drives the movement of the first finger bases 42, 43. The first moving rail 41 is arranged along the X axis, and the pair of fingers 44, 45 in the front stage are attached to the pair of first finger bases 42, 43. When the first actuator 40 is driven, the pair of fingers 44, 45 in the front stage are opened and closed along the X axis together with the pair of first finger bases 42, 43.

[0015] The pair of fingers 94, 95 at the rear stage are supported on the rear side of the hand base 31 via two actuators (a second actuator 50 and a third actuator 60). The second actuator 50 is a motor-driven linear actuator and includes a linear second moving rail 51 and a second moving block 53 that is movable along the second moving rail 51. The third actuator 60 is an air-driven actuator and includes an air cylinder body 61 and a piston rod 63 that reciprocates relative to the air cylinder body 61. The second moving rail 51 is disposed along the Y-axis, and the air cylinder body 61 is attached to the second moving block 53 via a connecting rod 55. The air cylinder body 61 is oriented so that the reciprocating direction of the piston rod 63 is the Y-axis direction. A finger support plate 65 that supports the pair of fingers 94, 95 at the rear stage is connected to the piston rod 63.

[0016] The second linear guide 25 has a linear second guide rail 26 and a second guide block 27 that is movable along the second guide rail 26. The second guide rail 26 is disposed along the Y-axis on the hand base 31 side, and the second guide block 27 is attached to a finger support plate 65 that supports a pair of subsequent fingers 94, 95.

[0017] The transmission mechanism 70 transmits the power that opens and closes the pair of fingers 44, 45 in the front stage to the pair of fingers 94, 95 in the rear stage, and has third and fourth linear guides 71, 75 that guide the movement of the pair of fingers 94, 95 in the Y-axis direction, and a fifth linear guide 81 that guides the opening and closing of the pair of fingers 94, 95 in the X-axis direction.

[0018] The fifth linear guide 81 has a linear fifth guide rail 83 and a pair of second finger bases 84, 85 that are movable toward and away from each other along the fifth guide rail 83. The fifth guide rail 83 is attached to the finger support plate 65 along the X-axis direction, and a pair of subsequent fingers 94, 95 are attached to the pair of second finger bases 84, 85.

[0019] The third linear guide 71 has a linear third guide rail 72 and a third guide block 73 that is movable along the third guide rail 72. The third guide rail 72 is arranged along the Y-axis direction, and one first finger base 42 of a pair of first finger bases 42, 43 is connected to an end portion of the third guide rail 72, and one second finger base 84 of a pair of second finger bases 84, 85 is connected to the third guide block 73. This allows one finger 94 of a pair of fingers 94, 95 in the rear stage to move in response to the movement of one finger 44 of a pair of fingers 44, 45 in the front stage.

[0020] The fourth linear guide 75 has a linear fourth guide rail 76 and a fourth guide block 77 that is movable along the fourth guide rail 76. The fourth guide rail 76 is arranged along the Y-axis direction, and the other first finger base 43 of the pair of first finger bases 42, 43 is connected to an end portion thereof, and the other second finger base 85 of the pair of second finger bases 84, 85 is connected to the fourth guide block 77. This allows the other finger 95 of the pair of fingers 94, 95 in the rear stage to move in response to the movement of the other finger 45 of the pair of fingers 44, 45 in the front stage.

[0021] According to the transmission mechanism 70 configured in this manner, the pair of fingers 94, 95 in the rear stage can be opened and closed in response to the opening and closing of the pair of fingers 44, 45 in the front stage.

[0022] The movement of the pair of fingers 94, 95 in the rear stage will be described below with reference to Figure 5. As shown in Figures 5(a) and 5(b), by driving the second actuator 50, the pair of fingers 94, 95 in the rear stage can be moved together with the third actuator 60 to any position between position Pa1 where the fingers 94, 95 are separated from the pair of fingers 44, 45 in the front stage and position Pa2 where the fingers 94, 95 are close to (in contact with) the pair of fingers 44, 45 in the front stage. As shown in Figures 5(a) and 5(c), by driving the third actuator 60, the pair of fingers 94, 95 in the rear stage can be further moved away from position Pa1 where the fingers 94, 95 are separated from the pair of fingers 44, 45 in the front stage.

[0023] As described above, according to the hand device 2 of this embodiment, the actuator for moving the rear pair of fingers 94, 95 is configured with two short-stroke actuators 50, 60 in two stages, rather than with a single long-stroke actuator, thereby increasing the travel distance of the rear pair of fingers 94, 95 while preventing the hand body 30 from becoming larger. In this case, configuring the second actuator 50 as a motor-driven actuator enables precise position control of the rear pair of fingers 94, 95, and configuring the third actuator 60 as an air cylinder. This increases the travel distance of the rear pair of fingers 94, 95 while minimizing the increase in weight of the hand body 30 compared to when the third actuator 60 is configured as a motor-driven actuator. Of course, it is not prohibited to configure the third actuator 60 as a motor-driven actuator or the second actuator 50 as an air cylinder.

[0024] Hereinafter, with reference to FIGS. 6 and 7 , the operation realized by the two pairs of fingers of the hand device 2 according to this embodiment will be described. As shown in FIGS. 6( a) and 6(b), when the first actuator 40 is driven and the front pair of fingers 44, 45 closes, the rear pair of fingers 94, 95 also closes accordingly. By utilizing this movement, as shown in FIGS. 7(a) and 7(b), the hand device 2 can clamp a workpiece using a so-called double-sided chuck, which closes both the front pair of fingers 44, 45 and the rear pair of fingers 94, 95. At this time, the workpiece may be gripped by the claw portions 48, 49, 98, and 99 of the fingers 44, 45, 94, and 95 as shown in FIG. 7(a), or by the finger bodies 46, 47, 96, and 97 of the fingers 44, 45, 94, and 95 as shown in FIG. 7(b).

[0025] As shown in FIGS. 6( a) and 6(c), the second actuator 50 can be driven to move the rear pair of fingers 94, 95 toward or away from the front pair of fingers 44, 45. As a result, as shown in FIG. 7(c), the hand device 2 can be used as a hand device that clamps a workpiece with a so-called one-sided chuck, in which the rear pair of fingers 94, 95 is moved toward the front pair of fingers 44, 45 while the positions of the front pair of fingers 44, 45 are fixed. Also, as shown in FIG. 7(d), the hand device 2 can be used as a hand device that separates two engaged workpieces by gripping one of the workpieces with the front pair of fingers 44, 45 and gripping the other workpiece with the rear pair of fingers 94, 95, and then moving the rear pair of fingers 94, 95 away from the front pair of fingers 44, 45. Of course, the hand device 2 can be used as a hand device that fits two separated workpieces together by holding one of the workpieces with the front pair of fingers 44, 45 and holding the other workpiece with the rear pair of fingers 94, 95, and then moving the rear pair of fingers 94, 95 closer to the front pair of fingers 44, 45.

[0026] 6( a) and 6(d), when the second actuator 50 has moved the pair of fingers 94, 95 in the rear stage to the separated position, the third actuator 60 can be driven to move the pair of fingers 94, 95 in the rear stage further away from the separated position with respect to the pair of fingers 44, 45 in the front stage. This allows the hand device 2 to clamp a workpiece longer than the stroke length of the second actuator 50, as shown in FIG.

[0027] As described above, the hand device 2 according to this embodiment can provide a highly versatile hand device 2 that can be used not only for gripping workpieces of various types and sizes, but also for separating two fitted workpieces, fitting two separated workpieces together, etc. Such a hand device 2 can be suitably used, for example, for removing parts from an assembly, replacing parts, etc.

[0028] The workpiece pushing operation by the hand device 2 according to this embodiment will be described below with reference to FIGS. 8 and 9 . When a hand equipped at the end of the robot arm mechanism 1 pushes a workpiece with excessive force, various problems, such as damage to the workpiece, damage to the hand, or malfunction of the robot arm mechanism 1, may occur. Therefore, it is important to control the force with which the workpiece is pushed. As shown in FIG. 8 , the force with which the workpiece is pushed can be controlled by providing at least one compression spring 100 between the hand body 30 and the connection plate 10. For example, when the hand device 2 is moved by the robot arm mechanism 1 and a workpiece pushing operation is initiated, a force similar to the force pushing the workpiece in the direction of contraction of the compression spring 100 acts on the compression spring 100 interposed between the connection plate 10 and the hand body 30. When the force pushing the workpiece exceeds the elastic force (biasing force) of the compression spring 100, the compression spring 100 begins to compress, and the hand body 30 is moved toward the connection plate 10. By detecting the distance Db by which the compression spring 100 has compressed, Hooke's law allows the load (Db x k) to be calculated as the pressing force Fb on the workpiece by multiplying the distance Db by the spring constant k specific to the compression spring 100. Of course, if multiple compression springs 100 are installed, the pressing force Fb can be calculated by adding up the loads (Db x k x n) where n is the number of compression springs. If multiple compression springs with different spring constants k are installed, the load of each compression spring is calculated, and the pressing force Fb can be calculated by adding up the loads.

[0029] The hand device 2 includes a means for detecting the distance by which the compression spring 100 is compressed and a means for calculating the force with which the hand device 2 pushes a workpiece based on the compressed distance of the compression spring 100. Here, the distance sensor 110 detects the distance between the connection plate 10 and the hand body 30 as the compressed distance of the compression spring 100. For example, as shown in FIG. 8 , the distance sensor 110 is provided on the back surface of the connection plate 10, facing the hand base 31. The distance sensor 110 may be a known sensor such as an optical sensor or an infrared sensor. Of course, the type of the distance sensor 110 and the location where the distance sensor 110 is installed are not limited to these. Various methods for detecting the compressed distance of the compression spring 100 may be employed. The function of the calculation unit may be implemented in a control device that controls the robot arm mechanism 1. By identifying the force by which the workpiece is pushed, the robot arm mechanism 1 can be controlled. For example, the robot arm mechanism 1 can be stopped when the force by which the workpiece is pushed exceeds a predetermined threshold. Furthermore, the workpiece can be pushed with a predetermined force.

[0030] The placement of the compression spring 100 between the hand body 30 and the connection plate 10 also provides the following effect. Specifically, when the hand device 2 pushes in a workpiece, the force pushing the workpiece can be gradually increased as the compression spring 100 contracts due to the robot's control of the movement of the hand device 2. This prevents push-in failures and reduces the possibility of damage to the workpiece or the robot. Thus, the hand device 2 according to this embodiment can achieve a workpiece pushing operation. For example, as shown in FIG. 9A , two pairs of fingers 44, 45, 94, 95 can simultaneously push in four push pins. Each finger may be composed of two or more finger bodies, in which case eight or more push pins can be simultaneously pushed in.

[0031] 9(b), the workpiece can be gripped by two pairs of fingers 44, 45, 94, 95 and pushed in while being gripped, i.e., it is possible to transition from a gripping operation to a pushing operation. The arrangement of the four pushing positions for the four push pins varies depending on the specifications, but even in such cases, the relative positions of the four fingers 44, 45, 94, 95 can be freely changed to push in the four push pins simultaneously.

[0032] The hand device 2 according to this embodiment includes two pairs of fingers 44, 45, and 94, 95. However, the hand device 2 may include three or more pairs of fingers. For example, a hand device including a total of three pairs of fingers, including a front pair of fingers 44, 45, a rear pair of fingers 94, 95, and another pair of fingers, may be configured as follows. The hand device includes another transmission mechanism for opening and closing the further pair of fingers in response to the opening and closing of the front pair of fingers 44, 45. The other transmission mechanism is configured similarly to the transmission mechanism 70 and transmits the power for opening and closing the front pair of fingers 44, 45 to the further pair of fingers. Of course, the other transmission mechanism may also transmit the power for opening and closing the rear pair of fingers 94, 95 to the further pair of fingers. The hand device also includes an actuator for driving the movement of a further pair of fingers to change the distance between the further pair of fingers and a subsequent pair of fingers 94, 95, and an actuator for extending the change in the distance between the further pair of fingers and the subsequent pair of fingers 94, 95.

[0033] The following supplementary notes are further disclosed regarding this embodiment and its modified examples. (Supplementary Note 1) The hand device 2 includes a hand base 31, a pair of fingers 44, 45 provided on the hand base 31, an actuator that drives the pair of fingers 44, 45 to open and close, and a biasing member 100 that biases the pair of fingers 44, 45 toward their tips. (Supplementary Note 2) In the hand device 2 described in Supplementary Note 1, the biasing member 100 is an elastic member. (Supplementary Note 3) In the hand device 2 described in Supplementary Note 2, the elastic member 100 is rubber or a compression spring. (Supplementary Note 4) In the hand device 2 described in Supplementary Note 2, the elastic member 100 is a compression spring, and the pressing force of the pair of fingers 44, 45 against the workpiece is determined by multiplying the contracted length of the compression spring 100 by the inherent spring constant of the compression spring 100. (Appendix 5) The hand device 2 described in any one of Appendices 1 to 4 further includes a connection plate 10 for connecting to the arm tip of the robot 1, the hand base 31 is supported on the connection plate 10 so as to be able to move toward and away from the hand base 31, and the biasing member 100 is interposed between the hand base 31 and the connection plate 10.

[0034] (Supplementary Note 6) The hand device 2 described in Supplementary Note 1 further includes a stopper 17 for limiting the maximum distance of the hand base 31 from the connection plate 10. (Supplementary Note 7) In the hand device 2 described in Supplementary Note 5, the hand base 31 is movable toward and away from the connection plate 10 by a linear guide 20 attached to the connection plate 10. (Supplementary Note 8) The hand device 2 described in Supplementary Note 1 further includes at least another pair of fingers 94, 95 supported by the hand base 31. The at least another pair of fingers 94, 95 opens and closes in response to the opening and closing of the pair of fingers 44, 45. (Supplementary Note 9) The hand device 2 described in Supplementary Note 8 further includes another actuator 50 for changing the distance between the pair of fingers 44, 45 and at least another pair of fingers 94, 95. (Supplementary Note 10) The hand device 2 described in Supplementary Note 9 further includes yet another actuator 60 for expanding the change in the distance between the pair of fingers 44, 45 and the at least another pair of fingers 94, 95. (Supplementary Note 11) In the hand device 2 described in Supplementary Note 10, the other actuator 50 is an electric actuator, and the further other actuator 60 is an air-driven actuator.

[0035] Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the invention or the concept and spirit of the present invention derived from the content of the claims and their equivalents. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0036] REFERENCE SIGNS LIST 1...robot arm mechanism, 2...hand device, 10...connection plate, 17...stopper, 20...first linear guide, 21...first guide rail, 22...first guide block, 25...second linear guide, 26...second guide rail, 27...second guide block, 30...hand body, 31...hand base, 40...first actuator, 41...first moving rail, 42, 43...first finger base, 44, 45...fingers, 46, 47...finger body, 48, 49...claw portion, 50...second actuator, 51...second moving rail, 53... Second moving block, 55...connecting rod, 60...third actuator, 61...air cylinder body, 63...piston rod, 65...finger support plate, 70...transmission mechanism, 71...third linear guide, 72...third guide rail, 73...third guide block, 75...fourth linear guide, 76...fourth guide rail, 77...fourth guide block, 81...fifth linear guide, 83...fifth guide rail, 84, 85...second finger base, 94, 95...fingers, 96, 97...finger body, 98, 99...claw portion, 100...compression spring.

Claims

1. A hand device comprising: a hand base; a pair of fingers provided on the hand base; an actuator that drives the pair of fingers to open and close; and a biasing member that biases the pair of fingers toward their tips.

2. A hand device according to claim 1, wherein said biasing member is an elastic member.

3. A hand device according to claim 2, wherein the elastic member is a rubber or compression spring.

4. A hand device according to claim 2, wherein the elastic member is a compression spring, and the pushing force applied to the workpiece by the pair of fingers is determined by multiplying the contracted length of the compression spring by a spring constant specific to the compression spring.

5. A hand device according to any one of claims 1 to 4, further comprising a connection plate for connection to the tip of a robot arm, the hand base being supported on the connection plate so as to be able to move towards and away from the hand base, and the biasing member being interposed between the hand base and the connection plate.

6. The hand device according to claim 5, further comprising a stopper for limiting a maximum distance of separation of said hand base from said connection plate.

7. A hand device according to claim 5, wherein said hand base is provided so as to be movable toward and away from said connecting plate by a linear guide attached to said connecting plate.

8. The hand device according to claim 1, further comprising at least another pair of fingers supported by said hand base, said other pair of fingers opening and closing in response to the opening and closing of said pair of fingers.

9. A hand device according to claim 8, further comprising another actuator for varying the distance between said pair of fingers and said at least another pair of fingers.

10. A hand device according to claim 9, further comprising a further actuator for expanding the change in distance between said pair of fingers and said at least another pair of fingers.

11. A hand device according to claim 10, wherein the other actuator is electrically driven and the further other actuator is air driven.

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