Universal joint

Abstract

To provide a universal joint that is rotatable to release external force, and can be positioned in the same posture when positioning is required.SOLUTION: A universal joint of the present disclosure is a universal joint 100 in which a pair of link members 10, 20 are connected via a rotary part 11, and comprises a constraint member 30 that is connected to one link member 10 of the pair of link members 10, 20, is movable toward the other link member 20 of the pair of link members 10, 20, and constrains the rotation of the rotary part 11 by pressing against the other link member 20.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a universal joint.

Background Art

[0002] In a device that releases the force during work contact in fitting work or the like with an elastic body, a technique for eliminating the sag of the work due to its own weight is known. For example, Patent Document 1 discloses a robot arm provided with locking means for locking the rotation of a joint.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors have found the following problems regarding the universal joint. When a universal joint having at least one joint grips and transports a gripping object, by making the joint portion rotatable, the external force received by the gripping portion and the like can be released. However, in the technique disclosed in Patent Document 1, the rotatable angle is small, and there is a possibility that the external force cannot be sufficiently released. Further, when moving the gripping object to a predetermined position using the universal joint or the like, it is necessary to position the gripping object by restricting the rotation of the gripping portion.

[0005] The present disclosure has been made in view of such problems, and an object thereof is to provide a universal joint that can release an external force by being made rotatable and can be positioned in the same posture when positioning is required.

Means for Solving the Problems

[0006] One aspect for achieving the above object is It is a universal joint, A pair of link members are connected via a rotating part. The system includes a restricting member that is connected to one of the pair of link members and is movable toward the other link member of the pair, and that restricts the rotation of the rotating part by pressing against the other link member. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a universal joint that can be rotated to release external forces and can be positioned in the same orientation when positioning is required. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of the universal joint according to Embodiment 1. [Figure 2] This is a schematic cross-sectional view of a universal joint in its free state. [Figure 3] This is a schematic diagram of a universal joint and the object being gripped during gripping. [Figure 4] This is a schematic diagram of a universal joint and the object being gripped when subjected to an external force. [Figure 5] This is a schematic cross-sectional view of the universal joint according to Embodiment 2 when subjected to an external force. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations will be omitted where necessary for clarity.

[0010] It should be noted that the right-handed XYZ Cartesian coordinate system shown in Figure 3 and other drawings is merely a convenient representation for explaining the positional relationships of the components. Typically, the positive Z-axis is vertically upward, and the XY plane is horizontal, and this is consistent across all drawings.

[0011] <Embodiment 1> Referring to Figure 1, the configuration of the universal joint according to Embodiment 1 will be described. Figure 1 is a schematic cross-sectional view of the universal joint according to Embodiment 1. As shown in Figure 1, the universal joint 100 includes a constraint member 30 and a linear motion mechanism 40. The universal joint 100 has a pair of link members 10, 20 connected via a rotating part 11. One of the link members of the pair of link members 10, 20 may be provided with a gripping portion at its end for gripping an object 200 (not shown). The universal joint 100 may also be used with a tool attached to the end of one of the link members of the pair of link members 10, 20. The universal joint 100 may also be used as a component of a parallel link mechanism. In this embodiment, the case in which a gripping portion is provided at the end of one of the link members of the pair of link members 10, 20 will be described. If a gripping portion is provided at the end of the link member, the universal joint 100 operates as a device that grips and transports the object to be gripped 200 with the gripping portion provided at its end, specifically, it operates as, for example, a robot arm.

[0012] The universal joint 100 includes a control unit (not shown). The control unit controls the movement of each component, such as the link member 10. The link member 10 is connected to the link member 20 at the pivot section 11. The link member 20 is rotatable about the pivot section 11. That is, the link member 20 is connected to the link member 10 via the pivot section 11 and is rotatable relative to the link member 10. In this embodiment, for simplicity, it is illustrated as a rotation with one degree of freedom, but by using a universal joint, a configuration that allows rotation with two degrees of freedom can be made. One end of the link member 20 is connected to the pivot section 11, and the other end is provided with a gripping section 21. The gripping section 21 grips an object to be gripped 200 (not shown). The gripping section 21 is, for example, a two-finger gripper, a magnetic gripper, or a suction gripper.

[0013] The linear motion mechanism 40 is fixed to the link member 10 and moves the constraint member 30 in a linear motion. The linear motion mechanism 40 is a linear actuator such as an air cylinder. The constraint member 30 is connected to the link member 10 via the linear motion mechanism 40 and is capable of moving linearly in the axial direction of the link member 10. That is, the constraint member 30 is movable from the link member 10 side toward the link member 20 side. The shape of the constraint member 30 is not particularly limited, but in the example shown in Figure 1, for example, it is cylindrical. In the example shown in Figure 1, the constraint member 30 is arranged to surround the end of the link member 10 having the rotating portion 11 and moves linearly along the axial direction of the link member 10.

[0014] The constraint member 30 is pressed against the link member 20 by the linear motion mechanism 40. When the constraint member 30 is pressed against the link member 20, as shown in Figure 1, the link member 10 and the link member 20 are bridged by the constraint member 30, and the rotation of the link member 20 relative to the link member 10 is restricted. Figure 2 is a schematic cross-sectional view of the universal joint in the free state. As shown in Figure 2, when the constraint member 30 is on the link member 10 side, that is, when the constraint member 30 is not in contact with the link member 20, the link member 20 is in a free state and can rotate freely around the pivot part 11.

[0015] Thus, in the universal joint 100 according to Embodiment 1, when the rotating part 11 is in a free state, the angle at which the rotating part 11 can rotate is sufficiently large, so external forces received from the outside can be sufficiently relieved. Furthermore, by locking the rotating part 11, the universal joint 100 can position the gripping part 21 provided at the end of the link member 20.

[0016] The linear motion mechanism 40 can linearly move the constraint member 30 along the longitudinal direction of the link member 10. As shown in FIG. 1, when the constraint member 30 is disposed at a position where the end of the constraint member 30 on the link member 20 side contacts the link member 20, the contact portion between the constraint member 30 and the link member 20 increases, and the rotation of the link member 20 is strongly constrained. On the other hand, when the constraint member 30 is disposed at a position where the end of the constraint member 30 on the link member 20 side does not contact the link member 20 while covering the end on the rotating portion 11 side of the link member 20, compared with the case where it is disposed at the position shown in FIG. 1, the rotation of the link member 20 is weakly constrained. Thus, by adjusting the position of the constraint member 30 by the linear motion mechanism 40, that is, by adjusting the overlapping degree between the constraint member 30 and the link member 20, the degree of constraint on the rotation of the link member 20 can be adjusted.

[0017] Next, referring to FIGS. 3 and 4, the operation of the universal joint 100 in a state of gripping the object to be gripped 200 will be described in more detail. FIG. 3 is a schematic diagram of the universal joint and the object to be gripped during gripping. FIG. 4 is a schematic diagram of the universal joint and the object to be gripped when an external force is applied.

[0018] In the example shown in FIG. 3, the case where the universal joint 100 grips and conveys one object to be gripped 200a from among a plurality of objects to be gripped 200 (200a to 200c) stacked in a overlapping manner in the container 300 will be described.

[0019] The universal joint 100 conveys the object to be gripped 200 by moving the link member 10 in a state where the gripping portion 21 grips the object to be gripped 200. As shown in FIG. 3, when the gripping portion 21 conveys the object to be gripped 200a, the link member 20 is left in a free state. The arrow shown in FIG. 4 indicates the direction of the external force received by the object to be gripped 200a from the object to be gripped 200b. As shown in FIG. 4, there may be a case where the object to be gripped 200a that the universal joint 100 intends to convey is stacked below another object to be gripped 200b. In such a case, when the link member 10 is moved in a state where the gripping portion 21 grips the object to be gripped 200a, as shown in FIG. 4, the object to be gripped 200a receives an external force from the object to be gripped 200b.

[0020] Since the link member 20 is in a free state, when an external force is applied to the object to be gripped 200a, as shown in FIG. 4, the link member 20 rotates in a direction in which the moment of the force about the rotation portion 11 as the rotation axis becomes smaller. Thus, the flexible joint 100 can release an external force when transporting the object to be gripped 200 or the like.

[0021] <Embodiment 2> FIG. 5 is a schematic cross-sectional view of the flexible joint according to Embodiment 2 when an external force is applied. The flexible joint 400 according to Embodiment 2 is different from the flexible joint 100 described in Embodiment 1 in that it includes a restraint member 50 instead of the restraint member 30. Since the other configurations are the same, the description thereof will be omitted as appropriate. While the restraint member 30 was configured using a rigid body, the restraint member 50 is configured using an elastic body. In the example shown in FIG. 5, the restraint member 50 is a rubber member. Also, the restraint member 50 may be a member having both an elastic body and a non-elastic body. The restraint member 50 may be, for example, a member in which the cylindrical portion is configured using an elastic body and the connecting portion with the linear motion mechanism 40 is configured using a non-elastic body.

[0022] The arrow shown in FIG. 5 indicates the direction of the external force received by the link member 20. When an external force is applied to the link member 20 while its rotation is restricted by the restraint member 50, since the restraint member 50 has an elastic body, it deforms as shown in FIG. 5 to release the external force. That is, even when the restraint member 50 is in a state of being pressed against the link member, it allows the rotation of the link member 20 to a predetermined extent or more by deforming itself. Therefore, the flexible joint 400 can provide appropriate flexibility in operations involving contact such as assembly.

[0023] In the example shown in Figure 5, the constraint member 50 is a cylindrical member positioned to cover the end of the link member 20 on the rotating portion 11 side. Therefore, when the link member 20 is subjected to an external force that includes a component perpendicular to the longitudinal direction of the link member 20, the constraint member 50 deforms, thereby releasing the external force. In other words, the constraint member 50 can release external forces acting on the link member 20 in various directions while restricting the rotation of the link member 20.

[0024] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of Symbols]

[0025] 10,20 (a pair of) link members 11 Rotating parts 21 Gripping part 30,50 Constraint members 40 Linear motion mechanism 100,400 Universal joint 200,200a~200c Grasped object 300 containers

Claims

1. A universal joint in which a pair of link members are connected via a rotating part, A restricting member is provided, which is connected to one of the pair of link members and is movable toward the other of the pair of link members, and which restricts the rotation of the rotating part by pressing against the other link member. The restricting member has an elastic body and, when subjected to an external force while pressed against the other link member, deforms itself to allow the rotation of the rotating part to exceed a predetermined limit. Universal joint.

2. The universal joint according to claim 1, wherein one of the pair of link members has a gripping portion at its end that can grip an object to be gripped.

3. The universal joint according to claim 1, wherein the restricting member is a cylindrical member that restricts the rotation of the rotating part by covering the rotating part so as to bridge the one link member and the other link member.

4. The constraint member is capable of moving linearly from one link member toward the other link member so as to cover the rotating portion. The degree to which the rotation of the rotating part is restricted can be adjusted by adjusting the position of the restricting member. The universal joint according to claim 1.

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