JP2004283946A - Gripping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gripping device capable of obtaining a mechanism for gripping a fine object with by appropriate force by a simple constitution and improving durability mechanically or electrically. <P>SOLUTION: In the gripping device 100, a first arm 10 and a second arm 12 formed of resin members are mounted to a fixed part 5 at their tips and grip the object by grappling it with the tips. A wire 6 is suspended on a first connection section 7a and second connection section 7b disposed on tip sides of centers of the first arm 10 and second arm 12. When the wire 6 is energized, shape recovering forces are transmitted as grappling forces to the first arm 10 and second arm 12 to allow the gripping of the object. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gripping mechanism. The present invention particularly relates to a micro gripper for gripping a fine object.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an actuator using a shape recovery force of a shape memory alloy as a power source has been known (for example, see Patent Document 1). Actuators using a shape memory alloy have features such as contributing to downsizing of the device, lightness, and quietness.
[0003]
[Patent Document 1]
JP 2003-3948 (full text)
[Patent Document 2]
JP-A-63-285339 (full text)
[0004]
[Problems to be solved by the invention]
However, although the shape memory alloy is kept high in rigidity by using a Ti—Ni-based material or the like, there is a possibility that an unexpectedly large load may cause breakage. In particular, when a shape memory alloy is used as an actuator, such an excessive load is relatively easily generated depending on a driving target, and thus there is a high need for a design that can avoid destruction in advance.
[0005]
The present invention has been made in view of such a situation, and an object of the present invention is to realize a mechanism for gripping a fine object with an appropriate force. Another object of the present invention is to realize a mechanism for gripping a fine object with a simple configuration. Still another object is to increase mechanically or electrically durability of a mechanism for gripping a fine object.
[0006]
[Means for Solving the Problems]
One embodiment of the present invention is a gripping device. This device is a device for gripping an object by being sandwiched between a first member and a second member, and uses a shape recovery force of the wire generated by a temperature change of the wire formed of a shape memory alloy as a holding force. An actuator mechanism provided to the first member and the second member, and a buffer mechanism for releasing extra force so that a force applied to the object by the pinching force falls within a predetermined range.
[0007]
This gripping device is a device generally called a micro gripper, and has a structure in which an object is sandwiched mainly by the tip portions of two arms (fingers) formed in a tweezer shape. "First member" and "second member" refer to the arms of the gripping device, and may be integrally formed as a whole. The actuator mechanism may include a shape memory alloy wire that converts thermal energy into mechanical energy. When the wire is energized, the wire generates heat by its electric energy, and a shape recovery force as mechanical energy may be generated based on the heat energy. The shape memory alloy may have a bidirectional shape memory effect. The wire may be hung on a specific portion of the first member and the second member, and the shape recovery force of the wire may act in the opening and closing directions of the first member and the second member.
[0008]
The "buffer mechanism" may be mechanically configured by giving a characteristic to at least one of the shape and structure of the first member and the second member, or by adding a separate member or configuration for buffering. It may be realized mechanically or electrically.
[0009]
For example, when gripping an object having a predetermined size and thickness, an appropriate clamping force is applied to the object. On the other hand, when an object that is larger than planned or thicker than planned is gripped, a force opposing the pinching force is applied to the first member and the second member larger or earlier than planned. According to this aspect, even when the resistance force of the target object is larger than expected, the extra force is released by the buffer mechanism. Accordingly, an unreasonable load is not applied to the wire made of the shape memory alloy, and the wire can be prevented from being cut. Such a mechanism can be realized with a relatively simple configuration, and the holding force applied to the object can be kept at an appropriate level.
[0010]
It is to be noted that any combination of the above-described components and any conversion of the expression of the present invention between a method, an apparatus, a system, and the like are also effective as embodiments of the present invention.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
The gripping device according to the present embodiment is a normally-open microgripper that is normally opened, and has a mechanism for gripping an object with the distal ends of two arms while the switch is turned on. Since this gripping device uses an actuator made of a shape memory alloy, it can be configured to be small and lightweight, and its operation is highly silent. Further, since the shape memory alloy can withstand boiling disinfection, this gripping device can be applied to a part of medical equipment. Further, since the force for gripping the target object can be suppressed to an appropriate force, it is also suitable for gripping a soft and fragile target object such as a living egg. Similarly, it is also suitable for gripping fragile objects such as IC chips and glass.
[0012]
FIG. 1 shows a basic structure of the gripping device according to the first embodiment. The gripping device 100 has a first arm 10, a second arm 12, a fixing part 5, and a wire 6. The first arm 10 and the second arm 12 are formed of a rod-shaped resin member, and their respective ends are connected to the fixing portion 5, and their respective ends bend left and right to sandwich the object. The first arm 10 and the second arm 12 are respectively provided with a first hook 7a and a second hook 7b on which the wire 6 is hooked. The fixed portion 5 is provided with a first engaging portion 8a and a second engaging portion 8b to which both ends of the wire 6 are attached. The first engaging portion 8a and the second engaging portion 8b are formed of metal and serve as electrodes for supplying electricity to the wire 6. The first engagement portion 8a and the second engagement portion 8b are connected to a power supply line 14, and a switch 16 and a power supply 18 are connected on a path of the power supply line 14. When the switch 16 is turned on, the wire 6 is energized from the power supply 18 via the power supply line 14.
[0013]
The wire 6 is formed of a shape memory alloy having a two-way shape memory effect, and a shape recovery force generated by a temperature change is transmitted to the first and second arms 10 and 12 as a displacement force in the opening and closing directions. That is, a displacement force is generated by converting thermal energy into mechanical energy by the shape memory alloy. Further, since current is supplied to the shape memory alloy in order to generate thermal energy, a displacement force is generated by converting electric energy into mechanical energy as a whole. The wire 6 is a shape memory alloy thin wire in which a contracted shape is stored.
[0014]
The first hooking portion 7a and the second hooking portion 7b are respectively provided at positions slightly distal from the centers of the elongated first arm 10 and the second arm 12, and the shape recovery force of the wire 6 is the first. The first arm 10 and the second arm 12 are transmitted in a direction to close the first arm 10 and the second arm 12 via the hook 7a and the second hook 7b.
[0015]
Here, the first connecting portion 4a and the second connecting portion 4b, which are portions near the ends attached to the fixing portion 5 of the first arm 10 and the second arm 12, are designed to have a certain degree of elasticity. This elasticity acts so that the first arm 10 and the second arm 12 bend in the closing direction when the wire 6 is energized and its shape recovery force acts as a clamping force. When the energized state of the wire 6 is released, the elasticity of the first connecting portion 4a and the second connecting portion 4b acts in the opening direction of the first arm 10 and the second arm 12, and the first arm 10 and the second Each of the two arms 12 is returned to the original position.
[0016]
The first arm 10 includes a first distal end portion 1a, which is a portion near the distal end thereof, and a first main column portion 3a, which extends from substantially the center to the distal end. , And is designed to be thinner than the surrounding first tip portion 1a and first main pillar portion 3a. This may be a design in which the width is simply reduced in a curved shape as shown in FIG. 2, or a design in which the width is reduced by providing a notch as shown in FIG. Similarly to the first arm 10, the second arm 12 also includes a second tip portion 1b, which is a portion near the tip, and a second main pillar portion 3b extending substantially from the center to the end, and is located therebetween. The second buffer portion 2b, which is a portion, is designed to be thinner than the surrounding second tip portion 1b and second main pillar portion 3b.
[0017]
The first buffer section 2a and the second buffer section 2b have a function of releasing extra force so that the force applied to the target object by holding the first arm 10 and the second arm 12 is within a predetermined range. That is, the first buffer 2a and the second buffer 2b are formed so as to ensure appropriate elasticity by designing their shapes. Thereby, when the size and thickness of the target object exceed the predetermined size and predetermined thickness and the resistance of the target object to the holding force becomes larger than expected, the extra force generated in the wire 6 is buffered so as not to cut the wire 6. can do.
[0018]
(2nd Embodiment)
The gripping device in the present embodiment is a normally-open type micro gripper that is normally opened similarly to the first embodiment, and holds the object between the distal ends of the two arms while the switch is turned on. It has a gripping mechanism. However, the second embodiment is different from the first embodiment in that one of the two arms is fixed and the other is movable.
[0019]
FIG. 4 shows a basic structure of the gripping device according to the second embodiment. Here, the first arm 10 is movable as in the first embodiment, whereas the second arm 12 is formed integrally with the fixed part 5. The first arm 10 is formed of a resin member having elasticity, while the second arm 12 is formed of a member having low elasticity. Therefore, the shape recovery force of the wire 6 generated when the wire 6 is energized is transmitted to the first arm 10 and the second arm 12 as a displacement force in the opening and closing direction, but only the movable first arm 10 bends. Displaced in the closing direction.
[0020]
Here, the connecting portion 4, which is a portion near the end of the first arm 10, is designed to have the bending of the first arm 10 and the elasticity for returning the same to the original state, as in the first embodiment. . The buffer 2, which is a portion located between the distal end 1, which is a portion near the distal end of the first arm 10, and the main pillar 3 from substantially the center to the distal end, as in the first embodiment. It is designed to be thinner than the part 1 and the main pillar part 3. An extra force is released by the buffer unit 2 so that the force applied to the target object by holding the first arm 10 and the second arm 12 is within a predetermined range.
[0021]
(Third embodiment)
Unlike the first and second embodiments, the gripping device of the present embodiment is a normally-closed micro gripper that is normally closed, and the interval between the two arms increases while the switch is turned on, and the switch is turned off. In this case, a mechanism is provided in which the distal ends of the two arms hold the object between the two arms.
[0022]
FIG. 5 shows a basic structure of the gripping device according to the third embodiment. The first distal end 1a and the second distal end 1b of the first arm 10 and the second arm 12 of the present embodiment are formed to be inclined in directions intersecting each other. It is formed in a shape. Normally, these vertical portions are formed such that surfaces facing each other are in close contact with each other, so that the first arm 10 and the second arm 12 are closed when power is not supplied, but the first distal end portion is supplied when power is supplied. 1a and the 2nd front-end | tip part 1b move to the opening direction. If the object is disposed between the first tip 1a and the second tip 1b when the power is released and the energization is released, the first tip 1a and the second tip 2a are resilient due to the elasticity of the first link 4a and the second link 4b. The tip 1b is displaced in the closing direction. By utilizing the force, the object can be held between the first distal end portion 1a and the second distal end portion 1b.
[0023]
The first shock absorber 2a and the second shock absorber 2b have elasticity as in the first embodiment, and have an extra force so that the force applied to the object by holding the first arm 10 and the second arm 12 is within a predetermined range. Let go of power. Thereby, the extra force generated in the wire 6 can be buffered so as not to cut the wire 6.
[0024]
In the present embodiment, the holding force of the first arm 10 and the second arm 12 for gripping the target object is not the shape recovery force of the wire 6 but the elasticity of the first connection portion 4a and the second connection portion 4b. We are using. Therefore, even if the size and thickness of the target object exceed the predetermined size and the predetermined thickness, no extra load is applied to the wire 6 due to the drag, and the wire 6 is not cut or broken.
[0025]
(Fourth embodiment)
The gripping device in the present embodiment is a normally-closed micro gripper that is normally closed as in the third embodiment, and when the switch is turned on, the interval between the two arms is widened and the switch is turned off. And a mechanism for sandwiching and grasping the object between the tips of the two arms. However, the third embodiment differs from the third embodiment in that one of the two arms is fixed and the other is movable, as in the second embodiment.
[0026]
FIG. 6 shows a basic structure of a gripping device according to the fourth embodiment. Here, the first arm 10 is movable as in the third embodiment, whereas the second arm 12 is integrally formed with the fixed portion 5 as in the second embodiment. Therefore, at the time of energization, only the first arm 10 bends and displaces in the closing direction. In addition, the configuration of the first arm 10 is the same as that of the first arm 10 in the third embodiment, and the first buffer 2a functions as a buffer mechanism.
[0027]
(Fifth embodiment)
In the gripping device according to the present embodiment, the shapes of the first arm 10 and the second arm 12 are different from those of the other embodiments. That is, the first arm 10 and the second arm 12 are designed so that the distance from the actuator mechanism to the part that grips the target is relatively long. This ensures that the first arm 10 and the second arm 12 have elasticity to absorb the extra force applied to them.
[0028]
FIG. 7 shows a basic structure of a gripping device according to the fifth embodiment. The first tip 1a and the second tip 1b of the first arm 10 and the second arm 12 are curved in such a manner as to partially detour so as to protrude outward. In this way, the distance from the first hooking portion 7a and the second hooking portion 7b to the part that grips the object is gained. Further, the first buffer 2a and the second buffer 2b have elasticity as in the first embodiment. Thereby, the first tip 1a and the second tip 1b, the first buffer 2a and the second buffer 2b function as a buffer mechanism as a whole. In addition, as long as the design is such that the distance from the actuator mechanism to the object is relatively long, the shapes of the first arm 10 and the second arm 12 are arbitrary as in the ninth embodiment and later described later.
[0029]
(Sixth embodiment)
The gripping device of the present embodiment is different from the first to fifth embodiments in that the buffer mechanism is realized by electric means.
[0030]
FIG. 8 shows the basic structure of the gripping device according to the sixth embodiment. The gripping device 100 has a first arm 10, a second arm 12, a wire 6, a switch 16, a power supply 18, an opening / closing mechanism 20, and a load resistor 26. The opening / closing mechanism 20 is configured to be always open with a fixed contact 22 and a movable contact 24, and is connected in parallel with the wire 6. The movable contact 24 is formed in a leaf spring shape and has elasticity. The load resistor 26 is connected in parallel with the switching mechanism 20. The power supply 18 and the switch 16 for energizing the wire 6 are provided on a path connecting the engaging portion 28 and the movable contact 24.
[0031]
The wire 6 is arranged along the outer peripheral surfaces of the first arm 10 and the second arm 12. One end of the wire 6 is attached to the engaging portion 28, and the other end is attached to the movable contact 24. When the switch 16 is turned on, the wire 6 is energized, and the first arm 10 and the second arm 12 are displaced in the closing direction by the shape recovery force of the wire 6 in the contraction direction. The contracting force in the closing direction is transmitted to the first arm 10 and the second arm 12 as a holding force.
[0032]
Here, when the size or thickness of the target object exceeds the predetermined size or predetermined thickness, the holding force to be transmitted to the first arm 10 and the second arm 12 succumbs to the drag of the target object earlier than planned. Therefore, an extra contraction force is generated in the wire 6. Although the engaging portion 28 is fixed in position, since the movable contact 24 has elasticity, an excessive contraction force of the wire 6 acts as a force to pull up the tip of the movable contact 24.
[0033]
The movable contact 24 pulled up by the wire 6 comes into contact with the fixed contact 22. By this contact, the normally open / close mechanism 20 is closed. The current that has been flowing to the wire 6 until then is distributed to the path connecting the engaging portion 28 and the fixed contact 22, and the flow of the current to the wire 6 is suppressed. That is, the electric energy supplied to the wire 6 is reduced. Thereby, the contraction force of the wire 6 is suppressed, so that the holding force applied to the first arm 10 and the second arm 12 is reduced, and the wire 6 is prevented from being cut by an extra force.
[0034]
On the other hand, a load resistor 26 is connected in parallel with the switching mechanism 20. Normally, when a contact through which a current is flowing is suddenly opened and closed even when the power supply voltage is low, sparks tend to fly instantaneously. This is due to the parasitic inductance of the circuit and the power supply, and causes damage to the contacts. Therefore, by arranging the load resistor 26 in parallel with the contact portion, damage, wear and deterioration of the contact can be prevented, and hunting of the actuator can be suppressed.
[0035]
When the heat generated by the wire 6 is transmitted to the first arm 10 and the second arm 12, the heat may be accumulated in the first arm 10 and the second arm 12. In this case, even if the current supply to the wire 6 is stopped, the heat of the first arm 10 and the second arm 12 does not allow the heat of the wire 6 to be easily cooled, and the shape recovery in the reverse direction may be delayed. Therefore, the outer peripheries of the first arm 10 and the second arm 12 are designed to be thin so as not to touch the wire 6 except for a particularly curved portion.
[0036]
(Seventh embodiment)
The gripping device of the present embodiment is common to the sixth embodiment in that the buffer mechanism is realized by electrical means, but is different from the sixth embodiment in that power supply to the actuator mechanism is controlled using a transistor as a switching circuit. This is different from the embodiment.
[0037]
FIG. 9 shows a basic structure of the gripping device according to the seventh embodiment. The gripping device 100 includes a first arm 10, a second arm 12, a wire 6, a switch 16, a power supply 18, an opening / closing mechanism 20, a load resistor 26, a transistor 27, and an urging spring 29. The wire 6 is arranged along the outer peripheral surfaces of the first arm 10 and the second arm 12. Both ends of the wire 6 are connected to both poles of a power supply 18 via a switch 16. The opening / closing mechanism 20 is configured as a normally closed type with a fixed contact 22 and a movable contact 24, and is connected in parallel with the wire 6. The term “parallel” as used herein means that the opening / closing mechanism 20 is electrically parallel to the wire 6. From a mechanical viewpoint, the fixed contact 22 is provided on a path connecting the wire 6 and the power supply 18, and the movable contact 24 is provided on a path parallel to the wire 6. One end of the wire 6 is attached to the engaging portion 28, and the other end is attached to the movable contact 24. The biasing spring 29 is a member having elasticity, and biases the movable contact 24 toward the fixed contact 22. As a result, the opening / closing mechanism 20 is normally closed.
[0038]
The transistor 27 is an npn-type bipolar transistor connected in series with the wire 6, the collector electrode of which is connected to one end of the wire 6 via the engaging portion 28, and the emitter electrode of which is connected to the power supply 18 via the switch 16. Connected to negative electrode. Further, the base electrode is connected to the fixed contact 22 of the switching mechanism 20 via the load resistor 31.
[0039]
When the switch 16 is turned on, the wire 6 is energized, and the first arm 10 and the second arm 12 are displaced in the closing direction by the shape recovery force of the wire 6 in the contracting direction. That is, the contraction force in the closing direction is transmitted to the first arm 10 and the second arm 12 as a holding force. At this time, since the opening / closing mechanism 20 is closed, the path connecting the fixed contact 22 and the base electrode of the transistor 27 is also energized. However, since the path is connected to the load resistor 31 and to the base electrode of the transistor 27 having a predetermined amplification factor, the base current is the current passing through the wire 6 according to the amplification factor. Settles at a weaker value. That is, the transistor 27 is arranged such that the current flowing from the movable contact 24 to the fixed contact 22 is weaker than the current flowing through the wire 6.
[0040]
Here, the size and thickness of the object may exceed the planned size and the planned thickness. In that case, the pinching force to be transmitted to the first arm 10 and the second arm 12 succumbs to the drag of the object earlier than expected, so that an extra contractive force is generated in the wire 6 and the wire 6 is cut. Or there is a risk of causing destruction. Further, if the switch 16 is kept on for a certain period of time or more, the wire 6 may be in an overheated state. Also in this case, there is a possibility that an excessive contraction force is generated in the wire 6 and the wire 6 is cut or broken.
[0041]
In the present embodiment, one end of the wire 6 on the side of the engaging portion 28 is fixed, but one end of the wire 6 on the side of the movable contact 24 is displaceably installed. Work as a pulling force. When the force of pulling the movable contact 24 due to the contraction force of the wire 6 exceeds the urging force of the urging spring 29, the opening / closing mechanism 20 is opened. The fixed contact 24 is turned off, and the base current of the transistor 27 stops flowing, so that the collector-emitter connection is cut off. Thereby, the supply of electric energy to the wire 6 is also cut off, the thermal energy generated by the wire 6 decreases with time, and cutting or breaking of the wire 6 is prevented.
[0042]
When the contraction force weakens as the heat energy generated by the wire 6 decreases, the urging force of the urging spring 29 gradually exceeds the contraction force of the wire 6 again, and the opening / closing mechanism 20 is closed. Thereafter, as the contraction force of the wire 6 increases and decreases, the opening and closing mechanism 20 repeats opening and closing. Generally, sparks are likely to fly in the opening and closing of such contacts, but in the present embodiment, the current passing between the contacts of the opening and closing mechanism 20 is sufficiently weakened by the arrangement of the transistor 27 and the load resistor 31. Sparks are difficult to fly. Therefore, damage, abrasion and deterioration of the contact can be prevented.
[0043]
(Eighth embodiment)
The holding device of the present embodiment is common to the seventh embodiment in that an opening / closing mechanism is connected in parallel to a wire. Hereinafter, a description will be given focusing on differences from the seventh embodiment.
[0044]
FIG. 10 shows the basic structure of the gripping device according to the eighth embodiment. The gripping device 100 includes a first arm 10, a second arm 12, a wire 6, a switch 16, a power supply 18, an opening / closing mechanism 20, and an urging spring 29. The opening / closing mechanism 20 is configured to be a normally closed type, and is connected to the wire 6 in series. The biasing spring 29 biases the movable contact 24 toward the fixed contact 22.
[0045]
When the switch 16 is turned on and the wire 6 is energized, the shape recovery force in the contraction direction of the wire 6 is transmitted to the first arm 10 and the second arm 12 as a clamping force. Here, when the size or thickness of the object exceeds the expected size or expected thickness, an extra contraction force generated in the wire 6 is generated, and the movable contact 24 is pulled up. When this force exceeds the urging force of the urging spring 29, the opening / closing mechanism 20 is opened and becomes non-conductive, so that the supply of electric energy to the wire 6 is cut off, and the cutting or breaking of the wire 6 is prevented. .
[0046]
(Ninth embodiment)
The gripping device according to the present embodiment is a normally-open type in which the distance from the actuator mechanism to the portion that grips the target is relatively long in the first arm 10 and the second arm 12 as in the fifth embodiment. Micro gripper. This ensures that the first arm 10 and the second arm 12 have elasticity to absorb the extra force applied to them.
[0047]
FIG. 11 shows the basic structure of the gripping device according to the ninth embodiment. The length of the first arm 10 and the second arm 12 is designed to be linearly longer than those of the other embodiments. The first buffer 2a and the second buffer 2b are located substantially at the center of the first arm 10 and the second arm 12, respectively. It has a linear shape such that the distance between the first arm 10 and the second arm 12 decreases from the first buffer 2a and the second buffer 2b toward the first tip 1a and the second tip 1b. In addition, the distance of the straight line portion is relatively long, and the distance from the first hooking portion 7a and the second hooking portion 7b to the part that grips the object is obtained. Further, since the first buffer 2a and the second buffer 2b have elasticity as in the first embodiment, the first distal end 1a and the second distal end 1b, the first buffer 2a and the second buffer 2a. 2b functions as a buffer mechanism as a whole.
[0048]
(Tenth embodiment)
The gripping device in the present embodiment is a normally-open microgripper in which the first arm 10 and the second arm 12 are formed in an elongated shape, similarly to the ninth embodiment. However, the second embodiment differs from the ninth embodiment in that one of the two arms is fixed and the other is movable, as in the second embodiment.
[0049]
FIG. 12 shows the basic structure of the gripping device according to the tenth embodiment. Here, the first arm 10 is movable as in the ninth embodiment, whereas the second arm 12 is integrally formed with the fixed portion 5 as in the second embodiment. Therefore, at the time of energization, only the first arm 10 is bent and displaced in the closing direction. In addition, the configuration of the first arm 10 is the same as that of the first arm 10 in the ninth embodiment, and the first buffer 2a functions as a buffer mechanism.
[0050]
(Eleventh embodiment)
Similar to the gripping device of the fifth embodiment, the gripping device of the present embodiment is configured such that the first distal end 1a and the second distal end 1b of the first arm 10 and the second arm 12 partially protrude outward. It is curved in such a way as to detour. However, the positions of the first buffer 2a and the second buffer 2b are different from those of the fifth embodiment.
[0051]
FIG. 13 shows the basic structure of the gripping device in the eleventh embodiment. A first buffer portion 2a is provided outside a substantially intermediate position from the first hooking portion 7a to the first connecting portion 4a, and similarly outside a substantially intermediate position from the second hooking portion 7b to the second connecting portion 4b. Is provided with a second buffer 2b. Therefore, the first tip 1a and the first hook 7a and the second tip 1b and the second hook 7b are located in different systems. The first buffer 2a and the second buffer 2b have elasticity as in the first embodiment. As described above, while increasing the distance from the first hooking portion 7a and the second hooking portion 7b to the region where the object is gripped, the holding force of the wire 6 is different from that of the first tip portion 1a and the second tip portion 1b. Is applied to the first hooking portion 7a and the second hooking portion 7b, and the influence of the holding force on the first tip portion 1a and the second tip portion 1b is small. Thus, the first tip 1a and the second tip 1b and the first buffer 2a and the second buffer 2b function as a buffer mechanism as a whole.
[0052]
(Twelfth embodiment)
As in the eleventh embodiment, in the gripping device of the present embodiment, the first distal end portion 1a of the first arm 10 is curved so as to protrude outward. However, the second embodiment differs from the eleventh embodiment in that one of the two arms is fixed and the other is movable, as in the second embodiment.
[0053]
FIG. 14 shows the basic structure of the gripping device in the twelfth embodiment. Here, the first arm 10 is movable as in the eleventh embodiment, whereas the second arm 12 is integrally formed with the fixed part 5 as in the second embodiment. Therefore, at the time of energization, only the first arm 10 bends and displaces in the closing direction. In addition, the configuration of the first arm 10 is the same as that of the first arm 10 in the eleventh embodiment, and the first buffer 2a functions as a buffer mechanism.
[0054]
(Thirteenth embodiment)
In the gripping device according to the present embodiment, similarly to the gripping device according to the eleventh embodiment, the first distal end 1a and the second distal end 1b of the first arm 10 and the second arm 12 are respectively connected to the first connecting portion 4a and the second connecting portion 4a. It is provided so as to bypass the system connecting the first hooking portion 7a and the system connecting the second connecting portion 4b and the second hooking portion 7b. However, while the first tip 1a and the second tip 1b of the eleventh embodiment are provided so as to protrude outward from the first hook 7a and the second hook 7b, respectively. The present embodiment is different in that it is provided in a shape protruding inward.
[0055]
FIG. 15 shows the basic structure of the gripping device in the thirteenth embodiment. A first buffer portion 2a is provided inside a substantially intermediate position from the first hooking portion 7a to the first connecting portion 4a, and similarly inside a substantially intermediate position from the second hooking portion 7b to the second connecting portion 4b. Is provided with a second buffer 2b. Therefore, the first tip 1a and the first hook 7a and the second tip 1b and the second hook 7b are located in different systems. The first buffer 2a and the second buffer 2b have elasticity as in the first embodiment. As described above, while increasing the distance from the first hooking portion 7a and the second hooking portion 7b to the region where the object is gripped, the holding force of the wire 6 is different from that of the first tip portion 1a and the second tip portion 1b. Is applied to the first hooking portion 7a and the second hooking portion 7b, and the influence of the holding force on the first tip portion 1a and the second tip portion 1b is small. Thus, the first tip 1a and the second tip 1b and the first buffer 2a and the second buffer 2b function as a buffer mechanism as a whole.
[0056]
(14th embodiment)
The gripping device according to the present embodiment is provided so that the first distal end portion 1a of the first arm 10 is detoured so as to protrude inward, similarly to the thirteenth embodiment. However, it differs from the thirteenth embodiment in that one of the two arms is fixed and the other is movable, as in the second embodiment.
[0057]
FIG. 16 shows the basic structure of the gripping device according to the fourteenth embodiment. Here, the first arm 10 is movable as in the thirteenth embodiment, whereas the second arm 12 is integrally formed with the fixed portion 5 as in the second embodiment. Therefore, at the time of energization, only the first arm 10 bends and displaces in the closing direction. In addition, the configuration of the first arm 10 is the same as that of the first arm 10 in the thirteenth embodiment.
[0058]
The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. . Such modified examples are described below.
[0059]
In the first to fifth, ninth to fourteenth embodiments, the positions of the first buffer part 2a, the second buffer part 2b, the first connecting part 4a, and the second connecting part 4b are shown in FIGS. However, the present invention is not necessarily limited to a configuration in which these portions have elasticity. Other specific portions of the first arm 10 and the second arm 12 may have elasticity to perform the same function, or the entire first arm 10 and second arm 12 may have elasticity to perform the same function.
[0060]
In each embodiment, the micro gripper is exemplified as the gripping device. However, the gripping device is not necessarily limited to gripping a fine object, and the gripping device may be applied to grippers of various scales.
[0061]
In the sixth embodiment, a configuration in which the opening / closing mechanism 20 is provided and an excessive contraction force generated in the wire 6 is avoided by electric means has been exemplified. In a modified example, an extra contraction force generated in the wire 6 may be mechanically avoided by using the elasticity of the movable contact 24 included in the opening / closing mechanism 20. That is, the movable contact 24 may be formed of an elastic member in the form of a leaf spring having elasticity to absorb the excess force of the wire 6, and one end of the wire 6 may be attached to the elastic member. As a result, the excessive contraction force generated in the wire 6 is absorbed by the movable contact 24.
[0062]
A normally open contact mechanism has been exemplified as the opening / closing mechanism 20 in the sixth embodiment. In a modified example, a normally-closed contact mechanism may be used, and in that case, the movable contact 24 may be pulled and the opening / closing mechanism 20 may be opened according to the contracting force of the energized wire 6. Further, the load resistor 26 in the modified example may be a variable resistor whose resistance value changes according to the shape recovery force of the wire 6.
[0063]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the durability of the holding | grip apparatus using a shape memory alloy can be improved mechanically or electrically.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a basic structure of a gripping device according to a first embodiment.
FIG. 2 is a diagram showing a configuration in which the width of a buffer is designed to be narrow in a curved shape.
FIG. 3 is a diagram showing a configuration in which a notch is provided in a buffer portion and the width thereof is designed to be narrow.
FIG. 4 is a diagram illustrating a basic structure of a gripping device according to a second embodiment.
FIG. 5 is a diagram illustrating a basic structure of a gripping device according to a third embodiment.
FIG. 6 is a diagram illustrating a basic structure of a gripping device according to a fourth embodiment.
FIG. 7 is a diagram illustrating a basic structure of a gripping device according to a fifth embodiment.
FIG. 8 is a diagram illustrating a basic structure of a gripping device according to a sixth embodiment.
FIG. 9 is a diagram illustrating a basic structure of a gripping device according to a seventh embodiment.
FIG. 10 is a diagram illustrating a basic structure of a gripping device according to an eighth embodiment.
FIG. 11 is a diagram showing a basic structure of a gripping device according to a ninth embodiment.
FIG. 12 is a diagram illustrating a basic structure of a gripping device according to a tenth embodiment.
FIG. 13 is a diagram illustrating a basic structure of a gripping device according to an eleventh embodiment.
FIG. 14 is a diagram illustrating a basic structure of a gripping device according to a twelfth embodiment.
FIG. 15 is a diagram illustrating a basic structure of a gripping device according to a thirteenth embodiment.
FIG. 16 is a diagram illustrating a basic structure of a gripping device according to a fourteenth embodiment.
[Explanation of symbols]
2 buffer part, 6 wires, 10 first arm, 12 second arm, 20 opening / closing mechanism, 22 fixed contact, 24 movable contact, 26 load resistance, 27 transistor, 100 gripping device.

Claims (12)

An apparatus for gripping an object by being sandwiched between a first member and a second member,
An actuator mechanism for applying a shape recovery force of the wire, which is generated by a temperature change of the wire formed of the shape memory alloy, to the first member and the second member as a holding force,
A buffer mechanism for releasing extra force so that the force applied to the object by the holding force falls within a predetermined range,
A gripping device comprising: 2. The gripping device according to claim 1, wherein the buffer mechanism is formed by giving at least one of the first member and the second member elasticity to absorb the extra force. 3. . The buffering mechanism is designed to secure elasticity for absorbing the extra force by designing at least one of the first member and the second member so that the thickness of a specific portion is smaller than the periphery of the specific portion. The gripping device according to claim 1, wherein the gripping device is formed. The buffering mechanism may be formed so that at least one of the first member and the second member is provided with a notch at a specific portion to secure elasticity for absorbing the extra force. The gripping device according to any one of claims 1 to 3, characterized in that: The said buffer mechanism is formed so that the elasticity which absorbs the said extra force may be ensured by designing the distance from the said actuator mechanism to the site | part which grips the said object comparatively long. The gripping device according to any one of 1 to 4. The said buffer mechanism is an elastic member which has the elasticity which absorbs the said extra force, and one end of the wire of the shape memory alloy contained in the said actuator mechanism is attached to the said elastic member, The Claims characterized by the above-mentioned. The gripping device according to claim 1. The gripping device according to claim 1, wherein the buffering mechanism reduces a holding force applied to the first member and the second member when the extra force is generated. The actuator mechanism is a mechanism that converts electrical energy into mechanical energy,
The gripping device according to claim 7, wherein the buffering mechanism reduces the holding force by reducing electrical energy supplied to the actuator mechanism when the extra force is generated. The buffer mechanism includes a normally-open type opening / closing mechanism connected in parallel with the actuator mechanism, and when the opening / closing mechanism is closed by the action of the extra force, the buffer mechanism has been supplied to the actuator mechanism until then. 9. The gripping device according to claim 8, wherein electric energy is distributed to a path to which the opening / closing mechanism is connected. The buffering mechanism includes a normally-closed opening / closing mechanism connected in series with the actuator mechanism, and when the opening / closing mechanism is opened by the action of the extra force, the buffer mechanism has been supplied to the actuator mechanism until then. The gripping device according to claim 8, wherein electric energy is cut off. The gripping device according to claim 9, wherein the buffering mechanism further includes a load resistor connected in parallel with the opening / closing mechanism. The buffer mechanism includes a normally-closed opening / closing mechanism connected in parallel with the actuator mechanism, and shuts off supply of electric energy to the actuator mechanism when the opening / closing mechanism is opened by the action of the extra force. A switching circuit,
9. The switching circuit according to claim 8, wherein the switching circuit is arranged such that a current passing between the contacts of the switching mechanism is weaker than a current passing through the wire when the switching mechanism is closed. Gripping device.

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