JP2006281403A - Gripping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gripping device which uses an actuator utilizing a shape memory alloy capable of greatly reducing the size and the weight of the gripping device, and has a furthermore long life, and can grip a very brittle object, and can be simply manufactured. <P>SOLUTION: The gripping device comprises a first driving section for contracting shape memory alloy wires 101 by heating them by supplying an electric current, a second driving section driven by an elastic means 103, an elastic force adjusting mechanism 106 for adjusting the elastic force of the elastic means 103, and a slider which is moved by being connected to the first and second driving sections. In this case, the elastic force caused by the elastic means 103 is applied in the direction for gripping the object, and the shape restoring forces caused by the shape memory alloy wires 101 are applied in the direction for releasing the object. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a gripping mechanism that grips an object.

Conventionally, various gripping mechanisms have been used in applications such as manipulators. For example, a pneumatic gripper using a pneumatic cylinder is known. In addition, an actuator using the shape recovery force of a shape memory alloy is known, and the present applicant has proposed a gripping device using a shape memory alloy (see Patent Document 1).
JP 2004-283949 A

However, the conventional shape memory alloy gripping mechanism can achieve a significant reduction in size and weight compared to pneumatic grippers, etc., but the gripping force cannot be freely adjusted, There are problems such as deterioration due to a load applied to the shape memory alloy wire when gripping. The present invention has been made in view of such problems. Another object of the present invention is to obtain a gripping device that is easy to manufacture.

The gripping device of the present invention is
Two arms for gripping the object;
A first drive unit for contracting the shape memory alloy wire by energization heating;
A second drive by elastic means;
An elastic force adjusting mechanism for adjusting the elastic force of the elastic means;
A slider connected to and operating on the first and second drive units;
A link mechanism for transmitting the movement of the slider to open and close the two arms;
With
The elastic force by the elastic means acts in the direction of gripping the object,
The shape recovery force by the shape memory alloy is a gripping device that acts in a direction to open the object.

By using a shape memory alloy as a drive source, the device has excellent characteristics such as downsizing and weight reduction and silent operation. Shape memory alloys generate very little magnetic field, are chemically stable and resistant to heat and chemicals, and therefore can be sterilized by boiling sterilization and can be used for medical devices.
In addition to the excellent effects of these shape memory alloy actuators, according to the gripping device of the present invention, the contraction force of the shape memory alloy wire moves the arm in the opening direction via the link mechanism, and the elastic force by the elastic means. Is configured to move the arm in the gripping direction, the gripping force can be freely changed by the elastic force adjustment mechanism, and when an unscheduled resistance is applied to the arm part due to a large object, for example, The elastic means acts as a buffer mechanism, can absorb extra force and reduce the load on the object. The arm may be provided with an elastic portion, so that extra force can be released as the second buffer mechanism, and a more secure gripping device can be configured. Due to the response speed at the time of energization heating of the shape memory alloy wire and the feature that a large force can be taken out from the start of the operation, the object can be quickly opened.
Furthermore, the grip position is accurately determined by using the link mechanism.
Further, it is a simple configuration that does not require the use of a motor, a cylinder, or the like, and can be easily manufactured.

Hereinafter, the gripping device of the present invention will be described with reference to the drawings.

In the present embodiment, the gripping device is in a state where the arm is closed when the shape memory alloy wire does not generate the shape recovery force.
Hereinafter, a state in which the shape memory alloy wire does not generate shape recovery force is referred to as a normal state, and a state in which shape recovery force is generated is referred to as shape recovery time.
FIG. 1 shows the structure of the present embodiment in the normal state.
The gripping device 100 includes a pair of arms 101, a shape memory alloy wire 102, a compression coil spring 103, a slider 104, a link mechanism 105, and a length adjustment mechanism 106. The arm 101 is connected to the slider 104 via the link mechanism 105.

FIG. 2 is a schematic view showing the structure of the link mechanism 105.
The slider 201 includes a guide groove 202 provided on the slider, an arm 203, a guide pin 204 provided at an upper end of the arm and engaged with the guide groove, and a support shaft 205 on which the arm is rotatably attached. .
When the slider 201 approaches and separates from the support shaft 205, the guide pin 204 changes the engagement position in the guide groove 202, and the pair of arms 203 perform a rotation operation around the support shaft 205. Can do. The shape of the guide groove 202 can determine the opening / closing direction of the arm with respect to the moving direction of the slider. In this embodiment, the arm is set to the closed state when approaching the support shaft 205.
With this structure, the arm 101 is opened and closed by the operation of the slider 104, and the arm 101 is normally closed.

FIG. 3 shows the structure at the time of shape recovery of this embodiment.
When the shape memory alloy wire 102 contracts due to energization heating, the slider 104 moves in a direction away from the support shaft, the arm 101 is opened via the link mechanism 105, and when the energization heating is released, the slider 104 is released. Moves in the approaching direction with respect to the support shaft, and the arm 101 is closed via the link mechanism 105.

By adopting this configuration, the arm 101 is opened by energizing and heating the shape memory alloy wire 102,
When the energization heating is released, the arm 101 is closed and operates to grip the object.
Since the gripping force is given by an elastic force, the gripping force can be freely adjusted by adjusting the length of the compression coil spring 103 by the length adjusting mechanism 106 attached to the compression coil spring 103.
When an extra load is applied to the object, the load is transmitted to the compression coil spring 103 through the arm 101 and the link mechanism 105 to absorb the load.
In addition, it is possible to realize a quick response speed by using a bi-directional shape memory alloy wire as the shape memory alloy used for the shape memory alloy wire 102 and further reduce the load applied to the shape memory alloy wire. .

In this embodiment, the gripping device is in a state where the arm is open in a normal state.
FIG. 4 shows the structure of the present embodiment in the normal state.
The gripping device 100 includes a pair of arms 101, a shape memory alloy wire 102, a compression coil spring 103, a slider 104, a link mechanism 105 ′, and a length adjustment mechanism 106. The arm 101 is connected to the slider 104 via a link mechanism 105 ′.
FIG. 5 shows the link mechanism 105 ′.
The shape of the guide groove is different from that of the link mechanism 105 of the first embodiment, and the arm is opened when the slider 104 approaches the support shaft.
Therefore, the slider 104 is operated so as to open the arm 101 when the elastic force of the compression coil spring is applied, and the arm 101 is closed by the shape recovery force of the shape memory alloy.

In particular, the gripping device according to the present embodiment is a device that grips a ring-shaped object.
First, the arm 101 that has been closed by energizing and heating the shape memory alloy wire 102 is inserted into the ring body.
Thereafter, when the energization heating of the shape memory alloy wire 102 is released, the arm 101 is opened by the elastic force of the compression coil spring 103, and the inside of the ring body is gripped by the arm 101.
According to this mechanism, it can be used as a gripping mechanism for a ring-shaped object, for example, a disc.

Similar to the first embodiment, this embodiment is a gripping device in which the arm is closed in a normal state, and is characterized in that an elastic portion is provided on the arm.
When an unexpected load such as a large object is applied, the compression coil spring absorbs the load, and the elastic part provided on the arm absorbs the object to grip a highly brittle object. Can reduce the load.

In addition, a present Example is an illustration and you may make this invention using another structure.

A gripping apparatus that can easily change a gripping force, can grip a highly brittle object more safely, and can be easily manufactured with a simple structure.

The figure which shows the closed state of the holding | gripping apparatus of Example 1. The figure which shows the link mechanism in Example 1. FIG. The figure which shows the open state of the holding | gripping apparatus of Example 1. The figure which shows the open state of the holding | gripping apparatus of Example 2. The figure which shows the link mechanism in Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Grasping apparatus 101 Arm 102 Shape memory alloy wire 103 Compression coil spring 104 Slider 105 Link mechanism 106 Length adjustment mechanism 201 Slider 202 Guide groove 203 Arm 204 Guide pin 205 Support shaft

Claims (6)

Two arms for gripping the object;
A first drive unit by shape recovery force of the shape memory alloy wire;
A second drive unit by the elastic force of the elastic means;
An elastic force adjusting mechanism for adjusting the elastic force of the elastic means;
A slider connected to and operating on the first and second drive units;
A link mechanism for transmitting the movement of the slider to open and close the two arms;
A gripping device comprising:
The elastic force by the elastic means acts in the direction of gripping the object,
2. The gripping device according to claim 1, wherein the shape recovery force by the shape memory alloy acts in a direction to open the object.
The gripping device according to claim 1, wherein the elastic force adjusting mechanism is a length adjusting mechanism.
4. The gripping device according to claim 1, wherein an elastic force by the elastic means acts in a direction in which the arm is closed.
4. The gripping device according to claim 1, wherein an elastic force by the elastic means acts in a direction in which the arm is opened.
The gripping device according to claim 1, wherein the arm is provided with an elastic portion.

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