JP2011067882A - Gripper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gripper achieving miniaturization. <P>SOLUTION: The gripper includes a driving source; and a conversion member for converting movement generated by the driving source to open-close movement for gripping a gripped object. The conversion member is comprised of a displacement enlarging member having a displacement enlarging function. This permits use of the driving source unsuitable for outputting a large displacement, such as a solenoid, thereby minimizing the gripper. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to, for example, a gripper that is mounted on an industrial robot and selectively grips a workpiece or the like, and more particularly, to a device that is devised so that the size can be reduced.

In general, a gripper for gripping a workpiece is an indispensable device for using an industrial robot. This type of gripper is required to have a sufficient gripping force for reliably gripping a workpiece and to be downsized. That is, if the gripper is small and light, the industrial robot can operate faster and more quickly.

Therefore, as the conventional gripper, an air gripper using an air cylinder that is very easy to downsize is often used. However, an air cylinder or the like using a high pressure air is required 10 times the electric power equipment by a pipe loss to high pressure air production and its air device by the compressor, supposed to be contrary to CO ₂ reduction of global warming End up. For that reason, advanced companies are removing air piping from factories.

  In the gripper, electric grippers have been commercialized as an alternative to conventional air grippers. However, those electric grippers have not been sufficiently miniaturized. For example, an excellent electric gripper is disclosed in Patent Document 1.

The electric gripper disclosed in Patent Literature 1 generates a gripping force by converting a rotational force of a rotary motor into a straight traveling direction using a cam and an inverted V-shaped member.

Another electric gripper is disclosed in Patent Document 2.

The electric gripper disclosed in Patent Document 2 generates a gripping force by converting a rotational force of a rotary motor into a straight traveling direction using a cam and a linear guide.

  Further, another electric gripper is disclosed in Patent Document 3.

The electric gripper disclosed in Patent Document 3 generates a gripping force by converting the rotational force of a rotary motor into a straight direction using a worm gear and a worm wheel gear.
Patent Document 3 is from the applicant of the present patent.

Japanese Patent No. 3469249 JP 2005-059118 A JP 2006-082141 A

The conventional configuration has the following problems. In other words, the electric grippers disclosed in Patent Document 1, Patent Document 2, and Patent Document 3 are all provided with excellent characteristics as a substitute for the conventional air gripper, but their miniaturization is insufficient. There was a problem that there was.

The present invention has been made based on such points, and an object thereof is to provide a gripper that can be miniaturized.

In order to achieve the above object, a gripper according to claim 1 of the present invention comprises a drive source, and a conversion member that converts a motion generated by the drive source into an opening / closing motion for gripping an object to be gripped. The conversion member is composed of a displacement enlarging member having a displacement enlarging function.
The gripper according to claim 2 is characterized in that, in the gripper according to claim 1, the conversion member is composed of a displacement enlarging member having a return spring function.
A gripper according to a third aspect is the gripper according to the first aspect, wherein the displacement enlarging member has a substantially linear spring characteristic.
A gripper according to claim 4 is the gripper according to claim 1, wherein a solenoid is used as the drive source.
According to a fifth aspect of the present invention, the gripper according to the first aspect is characterized in that the displacement enlarging member is a plate spring.
According to a sixth aspect of the present invention, the gripper according to the fifth aspect is characterized in that a substantially U-shaped elastic body is used as the displacement enlarging member.

As described above, according to the gripper according to claim 1 of the present invention, it comprises a drive source, and a conversion member that converts the motion generated by the drive source into an opening / closing motion for gripping an object to be gripped, Since the conversion member is composed of a displacement magnifying member having a displacement magnifying function, it becomes possible to use a drive source, such as a solenoid, that is not suitable for producing a large displacement, thereby reducing the size of the gripper. Can do.
Further, the gripper according to claim 2 is the gripper according to claim 1, wherein the conversion member is composed of a displacement enlarging member having a return spring function, so there is no need to provide a separate return spring, thereby The gripper can be downsized.
The gripper according to claim 3 is the gripper according to claim 1, wherein the displacement enlarging member is configured to have a substantially linear spring characteristic. For example, when a solenoid is used as a drive source, The suction force can be used more effectively, the power consumption of the solenoid can be reduced, and the gripper can be downsized.
According to a fourth aspect of the present invention, when the gripper according to the first aspect is configured such that a solenoid is used as the drive source, the gripper greatly contributes to downsizing of the gripper.
According to a fifth aspect of the present invention, when the displacement enlarging member is a plate spring, the desired effect can be obtained with a relatively simple structure.
According to a sixth aspect of the present invention, the gripper according to the fifth aspect of the present invention uses the substantially U-shaped elastic body as the displacement enlarging member, so that a desired effect can be obtained with a relatively simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the 1st Embodiment of this invention, FIG. 1 (a) is a sectional side view which shows the structure of a gripper, FIG.1 (b) is a bb arrow line view of FIG. (C) is a cc arrow line view of Fig.1 (a). It is a figure which shows the 1st Embodiment of this invention, and is a block diagram which shows the structure of the solenoid drive coil and the power supply device for solenoid drive devices. It is a figure which shows the 1st Embodiment of this invention, and is a figure which shows the voltage transient fluctuation | variation at the time of switching from DC24V to DC5V. It is a figure which shows the 1st Embodiment of this invention, and is a figure which shows the voltage transient fluctuation | variation at the time of switching from DC24V to DC5V. It is a figure which shows the 1st Embodiment of this invention and is a characteristic view which shows the relationship between a spring reaction force and a gap amount. 6A and 6B are views showing a second embodiment of the present invention, in which FIG. 6A is a side cross-sectional view showing the configuration of the gripper, FIG. 6B is a view taken along the line bb in FIG. c) is a cc arrow line view of Drawing 6 (a).

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, there is a solenoid housing 1, and a pair of solenoids 3, 3 as a drive source is condensed and arranged in the solenoid housing 1. In the case of this embodiment, the pair of solenoids 3 and 3 are arranged side by side in a direction orthogonal to the sheet of FIG. 1 (a), thereby reducing the thickness in the vertical direction in FIG. 1 (a). It is intended to realize.

Of the pair of solenoids 3, 3, the solenoid 3 disposed in front of FIG. 1A is composed of a coil 5 and a movable portion 7 disposed on the inner peripheral side of the coil 5. Yes. The front end portion of the movable portion 7 (the right side in FIG. 1A) is a tapered portion 7a having a tapered shape. A seating portion 9 is installed on the solenoid housing 1 side facing the taper portion 7a of the movable portion 7. The seating portion 9 is also formed with a tapered portion 9a. A gap 11 is formed between the tapered portion 7 a of the movable portion 7 and the tapered portion 9 a of the receiving portion 9.
Of the pair of solenoids 3, 3, the solenoid 3 on the back side in FIG. 1A has the same configuration, and the same portions are denoted by the same reference numerals.
However, the direction of the pair of solenoids 3 and 3 (drive direction of the movable parts 7 and 7) is opposite.

Of the pair of solenoids 3, 3, the rear end {the left end in FIG. 1 (a)} of the movable part 7 of the solenoid 3 disposed in front of FIG. An elastic body (conversion member) 13 is connected. The U-shaped elastic body 13 is made of a thin plate material (for example, a spring material such as stainless steel or phosphor bronze). One end 13 a of the U-shaped elastic body 13 is fixed to the solenoid housing 1. A holding member 15 is fixed to the other end 13 b of the U-shaped elastic body 13.
Of the pair of solenoids 3, 3, the U-shaped elastic body 13 and the gripping member 15 having the same configuration are attached to the movable portion 7 of the solenoid 3 on the back side in FIG. .

For example, in the solenoid 3 arranged on the front side in FIG. 1A, when a current is passed through the coil 5, the movable portion 7 has a small gap 11 provided on the right side in FIG. Is sucked in the direction. Thereby, the movable part 7 is driven in the right direction in FIG.
On the other hand, for example, in the solenoid 3 arranged on the back side in FIG. 1A, when a current is passed through the coil 5, the movable portion 7 has a small gap 11 provided on the left side in FIG. Is sucked in the direction. Thereby, the movable part 7 is driven leftward in FIG.

Next, a configuration of a power supply device 31 for driving the solenoid (solenoid including the solenoid housing 1, the movable portion 7, and the coil 5) 3 will be described with reference to FIG. As shown in FIG. 2, the power supply device 31 includes a 24 VDC power source 33, a 5 VDC power source 35, a relay 37, a timer 39, and a capacitor (capacitor) 41. The 24 VDC power source 33 does not need to be separately prepared, for example, when it is drawn from a power source for a linear actuator (not shown). The 5VDC power source 35 is produced by a small and compact DC / DC converter. In the case of the present embodiment, the overexcitation magnification is 4.8 times as shown in the following formula (I).
24V ÷ 5V = 4.8-(I)

Then, at the initial driving of the exciting coil 5, the movable portion 7 is vigorously attracted by a high voltage (overexcitation, in this embodiment, 24V). On the other hand, when the movable part 7 comes close to the seating part 9, it is configured to suppress heat generation by switching to a low voltage (normal excitation, 5V in this embodiment). Therefore, the solenoid 3 can be further downsized by using this overexcitation power source.

Switching between overexcitation and normal excitation is performed by the relay 37 and timer 39. In other words, the time for overexcitation by the timer 39 is set in advance, and when the set time elapses, the relay 37 is operated to switch the contact point 37a, thereby switching from overexcitation to normal excitation. It is to switch.
In the present embodiment, a relay with a contact (contact 37a) is used as the relay 37, but a contactless FET relay or the like may be used in addition to that.

Even if it is the contact relay 37 like this Embodiment, or a non-contact FET relay, the switching is high-speed. However, there is a concern that at the time of switching, the excitation voltage does not smoothly shift from 24V to 5V and the excitation voltage drops to 5V or less. This will be described with reference to FIG. FIG. 3 is a graph showing a change in voltage when switching from over-excitation to normal excitation (voltage transient fluctuation when switching from 24 V to 5 V) with time (ms) on the horizontal axis and voltage (V) on the vertical axis. It is. As shown in FIG. 3, it can be seen that the switching voltage does not smoothly shift from 24 V to 5 V at the time of switching, and the excitation voltage has dropped to 5 V or less. When such a phenomenon occurs, the sucked movable part 7 returns.

Therefore, in this embodiment, a capacitor (capacitor) 41 is connected in parallel to the exciting coil 5. As a result, the time constant of the circuit is increased to smoothly shift from 24V to 5V. The voltage change at that time is shown in FIG. FIG. 4 also shows time (ms) on the horizontal axis and voltage (V) on the vertical axis, and changes in voltage when switching from over-excitation to normal excitation (voltage transient fluctuation when switching from 24 V to 5 V). It is. As shown in FIG. 4, it can be seen that the transition is smoothly made from 24 V to 5 V at the time of switching, and the excitation voltage does not drop to 5 V or less.

In the case of this embodiment, as already described, by using the U-shaped elastic bodies 13 and 13 as conversion members having a return spring function, a separate spring component for return is required separately from the conversion member. Since the configuration is such that the gripper can be downsized. The U-shaped elastic bodies 13 and 13 exhibit substantially linear spring characteristics, that is, the greater the amount of deformation, the greater the restoring force (spring force). It can return to its original shape smoothly.

Further, when the U-shaped elastic bodies 13 and 13 are deformed, the solenoids 3 and 3 which are driving sources can be used with high efficiency. This will be described with reference to FIG. FIG. 5 is a diagram showing the relationship between the horizontal axis indicating the amount (mm) of the gap 11 and the vertical axis indicating the attractive force of the solenoid 3 and the spring reaction force of the U-shaped elastic body 13. In FIG. 5, the diagram a shows the attractive force of the solenoid 3, and the diagram b shows the spring reaction force of the U-shaped elastic body 13.

As shown in FIG. 5, the driving force (suction force) of the solenoid 3 is not constant and increases rapidly as the gap 11 becomes narrower. Further, the spring reaction force of the U-shaped elastic body 13 having a substantially linear spring characteristic increases as the gap 11 decreases (when the deformation amount increases), as in the solenoid 3. Therefore, as shown in FIG. 5, when the deformation of the U-shaped elastic body 13 is small, the spring reaction force is small, and the driving force (suction force of the solenoid 3) required for the deformation is small. On the other hand, when the deformation of the U-shaped elastic body 13 increases, a large driving force (solenoid 3 suction force) required for the deformation is required. That is, by using the U-shaped elastic body 13 having a substantially linear spring characteristic as the conversion member, the suction force of the solenoid 3 can be used more effectively, and the power consumption of the solenoid 3 can be reduced. In addition, downsizing can be realized.

Further, by using a plate-like elastic body as the U-shaped elastic body 13, the rigidity in the left-right direction in FIG. 1A is low, and the rigidity in the direction perpendicular to the paper surface in FIG. Yes. Thereby, it can restrict | limit so that it may deform | transform only in the left-right direction in Fig.1 (a), and what is called an elastic guide can be comprised. Therefore, the linear guide which has been conventionally required can be omitted.

The operation and effect will be described based on the above configuration.
First, when the coil 5 is energized in the solenoid 3 arranged on the near side along the direction orthogonal to the sheet of FIG. 1A, the movable part 7 moves to the right in FIG. Then, the portion b of the U-shaped elastic body 13 is pulled in the right direction in the figure. The U-shaped elastic body 13 rotates about the a part as a center, and the c part also moves in the right direction in FIG. Therefore, the gripping member 15 fixed to the other end of the U-shaped elastic body 13 on the c portion side also moves to the right in FIG.

On the other hand, when the coil 5 is energized in the solenoid 3 arranged on the far side along the direction orthogonal to the paper surface in FIG. 1A, the movable part 7 moves to the left in FIG. Then, the portion b of the U-shaped elastic body 13 is pulled leftward in FIG. The U-shaped elastic body 13 rotates about the a part as a center, and the c part also moves to the left in the figure. Therefore, the holding member 15 fixed to the other end of the U-shaped elastic body 13 on the c portion side also moves to the left in FIG.

That is, by passing a current through the coils 5 and 5 of the pair of solenoids 3 and 3, the left gripping member 15 in FIG. 1A moves to the right, and the right gripping member 15 in FIG. 1A moves to the left. As a result, the interval between the gripping members 15 and 15 becomes narrow, and if there is a workpiece (not shown) between the gripping members 15 and 15, it can be gripped.

At this time, since the U-shaped elastic bodies 13 and 13 rotate about the a portion, the displacement of the c portion is larger than the displacement of the b portion due to the principle of the lever. The enlargement ratio is approximately represented by the following formula (II).
Expansion ratio _{= L a-c / L a} -b --- (II)
However,
L _a-c : Distance between a part and c part L _ab : Distance between a part and b part

In addition, since the gripping members 15 and 15 are attached to one side of the c portion side of the U-shaped elastic bodies 13 and 13, the enlargement ratio at the d point of the gripping members 15 and 15 is expressed by the following formula (III). Can be as big as
Expansion ratio _{= L a-d / L a} -b --- (II)
However,
L _a-d : Distance between a part and d part L _ab : Distance between a part and b part

Thus, since the U-shaped elastic bodies 13 and 13 have a displacement expanding function, even the solenoids 3 and 3 that are not suitable for producing a large displacement can be used. That is, application of the solenoids 3 and 3 which are driving sources advantageous for downsizing becomes easier.
In addition, the a portion of the U-shaped elastic bodies 13 and 13 is deformed in a direction in which the bending angle becomes smaller by passing a current through the coils 5 and 5, so that the greater the deformation, the greater the reaction force. Linear spring characteristics are shown. Therefore, when energization of the coils 5 and 5 is stopped, the reaction force quickly returns to the original position.
Further, as shown in this embodiment, by using the U-shaped elastic bodies 13 and 13 as the displacement enlarging members having a return spring function, not only the displacement enlarging but also the return enlarging. This makes it possible to reduce the size of the gripper.
The substantially U-shaped elastic bodies 13 and 13 exhibit a substantially linear spring characteristic. Therefore, the greater the amount of deformation, the greater the restoring force (spring force). The shape can be returned to.
Further, the solenoids 3 and 3 which are driving sources can be used with high efficiency because of the substantially linear spring characteristics.
Thus, in the case of this embodiment, since a complicated mechanism such as a gear or a cam is not used, not only the miniaturization is easy, but there is no friction of the gear or the cam, and the mechanical efficiency due to the friction loss. Not only can the reduction be reduced, but also a reduction in size can be realized, and further reduction in size and reduction in power consumption can be realized by using a displacement enlarging member having a substantially linear return spring characteristic and a solenoid as a drive source.

Next, a second embodiment of the present invention will be described with reference to FIG. In the case of this second embodiment, for example, in the solenoid 3 arranged on the near side along the direction orthogonal to the middle page of FIG. 6A, the tip of the movable portion 7 is reduced in diameter. The diameter-reduced portion 7b is formed so as to penetrate the seating portion 9 and project and be arranged outside the solenoid housing 1. And the enlarged diameter part 7c is formed in the protrusion and arrangement | positioning part, and the U-shaped elastic body 13 is adhering to this enlarged diameter part 7b.
Further, the solenoid 3 disposed on the back side along the direction orthogonal to the sheet surface of FIG. 6A has the same configuration, and the same portions are denoted by the same reference numerals.

According to the above configuration, when current is passed through the coil 5 in the solenoid 3 on the near side along the direction orthogonal to the sheet of FIG. 6 (a), the movable portion 7 has a direction in which the gap 11 becomes narrow, that is, FIG. (A) It moves to the middle left side and pushes the U-shaped elastic body 13 arranged on the left side in FIG. 6 (a) to the left side. On the other hand, in the solenoid 3 on the back side along the direction orthogonal to the paper surface in FIG. 6A, when a current is passed through the coil 5, the movable part 7 moves in the direction in which the gap 11 becomes narrow, that is, in FIG. ) Move to the middle right side and push the U-shaped elastic body 13 on the right side in FIG. 6A to the right side. That is, when the coils 5 and 5 are energized, the grip members 15 and 15 are moved away from each other, and as a result, the pair of grip members 15 and 15 are opened.

On the other hand, when the current to the coil 5 is interrupted in the solenoid 3 on the near side along the direction perpendicular to the paper surface of FIG. 6A, the movable part 7 is moved by the elastic restoring force of the U-shaped elastic body 13. It returns to the direction in which the gap 11 becomes wider, that is, the right side in FIG. On the other hand, in the solenoid 3 on the back side along the direction orthogonal to the paper surface of FIG. 6A, when the current to the coil 5 is interrupted, the movable part 7 is caused by the elastic restoring force of the U-shaped elastic body 13. It returns to the direction in which the gap 11 becomes wider, that is, the left side in FIG. That is, when the energization of the coils 5 and 5 is interrupted, the gripping members 15 and 15 move in a direction approaching each other, and as a result, the pair of gripping members 15 and 15 are closed.

In the second embodiment, the operation of the solenoids 3 and 3 is the reverse of the operation in the first embodiment. Even in such a case, the first operation is performed. The same effects as those of the embodiment can be obtained.

The present invention is not limited to the first and second embodiments.
For example, in the first and second embodiments, a strip-shaped plate material is bent and used as the U-shaped elastic body, but the present invention is not limited to this shape. It is also possible to adjust the spring reaction force by giving a notch to the part or changing the width, and relatively flattening the rigidity of the flat part etc. Realization is possible.
In the first and second embodiments, the tip of the solenoid movable portion and the corresponding housing seating portion are tapered. However, even if the taper is not formed and flattened, the gap amount is increased. Needless to say, it can be implemented.
In the first and second embodiments, two solenoids are used. However, it is also conceivable to use a double solenoid that integrates these functions, thereby enabling further miniaturization.
Further, there are cases where gripping can be made more stable by using three or four or more depending on the workpiece shape.
Moreover, although the implementation example of the solenoid is given as the drive source, this is merely an example, and other drive systems are not excluded.

The present invention relates to a gripper that is a gripping device for a workpiece or the like used for an industrial robot, for example, and particularly relates to a device that has been devised so as to be able to reduce its size, for example, for industrial use installed in a narrow space. Suitable for robots.

1 Solenoid housing 3 Solenoid 5 Coil 7 Movable part 13 U-shaped elastic body

Claims (6)

A driving source, and a conversion member that converts the movement generated by the driving source into an opening / closing movement for gripping an object to be grasped,
The gripper characterized in that the conversion member is composed of a displacement enlarging member having a displacement enlarging function. The gripper of claim 1,
The gripper characterized in that the conversion member is composed of a displacement enlarging member having a return spring function. The gripper of claim 1,
The gripper characterized in that the displacement enlarging member has a substantially linear spring characteristic. The gripper of claim 1,
A gripper using a solenoid as the drive source. The gripper of claim 1,
The gripper characterized in that the displacement enlarging member is a plate spring. The gripper according to claim 5,
A gripper using a substantially U-shaped elastic body as the displacement enlarging member.

Images