CN102878195A - Two-degree-of-freedom hinged joint with single-direction return function - Google Patents

Abstract

A two-degree-of-freedom articulated joint with a reset function belongs to a wire rope connection reset device for a mechanical arm end effector using a wire rope soft capture method. The articulated joint consists of a shell (2) (9), a central slotted cylinder (6), and a rotating shaft (4) to form a two-degree-of-freedom joint, and an automatic reset device composed of a reset spring (3) and a reset torsion spring (5). . Its characteristic is that the axis of rotation in both directions of the joint is at the same point, and the return spring (3) and the return torsion spring (6) are added on the basis of the ordinary joint, so that the steel wire connected by the joint ( 8) It can automatically return to the initial position after turning.

Description

Two-degree-of-freedom articulated head with one-way reset function

technical field

The invention belongs to a wire rope connection reset device of a mechanical arm end effector adopting a wire rope soft capture method

technical background

In the field of aerospace, there is a mechanical arm end effector, which uses three wire ropes to rotate each other to achieve soft capture of the adapter. The two ends of each wire rope are respectively hinged on two concentric rings that can rotate relative to each other. In the initial state, the three wire ropes are evenly distributed in the inner groove of the ring and are close to the inner wall of the ring. When the two rings rotate relative to each other, The steel wire rope rotates in a plane approximately perpendicular to the axis of the ring, and the space surrounded by the three steel wire ropes gradually shrinks, finally completing the grabbing of the large end of the adapter rod section. When the end effector capture mechanism is reset, the wire rope is required to return to the initial position so that the next capture task can be successfully completed.

Since the wire rope has a tension process after the capture is completed, at this time the end of the adapter rod has a force parallel to the axis of the ring on the wire rope. Since the angle between the wire rope and the rod of the adapter is approximately equal to 90°, this force is parallel to the axis of the ring When the force in the direction is decomposed to the steel wire rope, a large force will be obtained. At this time, the steel wire rope will rotate at a certain angle on a plane parallel to the axis of the ring. When the tensioning process is released, the steel wire rope is required to return to the initial plane position in order to catch and release When the steel wire rope can smoothly get back in the groove of the ring inner wall.

The articulated joint used in the existing end-effector capture mechanism is connected by dislocation of two mutually perpendicular shafts, and the end of the wire rope joint is perforated and directly connected to the outermost shaft of the articulated joint. This hinged joint has several defects: it only has two degrees of freedom of rotation, and it does not have the function of spring automatic reset. When the capture mechanism repeats its work many times, it often occurs that the wire rope cannot return smoothly to the groove on the inner wall of the ring; The mechanism has very strict requirements on the length of the three steel wire ropes, which makes it more difficult to fix the steel wire ropes and joints; the tension of the steel wire ropes is decomposed into two disjoint spatial forces after passing through the joint, so that the shaft at the end will be additionally subjected to a The action of bending moment will easily cause uneven stress on the shaft mounting hole.

Contents of the invention

Purpose of the invention: the hinged joint of the wire rope of the existing catch mechanism cannot be automatically reset, and the length of the wire rope cannot be adjusted freely. On the basis of the traditional spherical joint, the present invention adds a return spring, a return torsion spring and an adjustable screw connection into the hinge joint to make up for the deficiency of the existing joint joint.

The technical scheme of the present invention: two shells with cylindrical grooves and spring leaf installation positions processed inside, one end of the shell has a semicircular extension section, and the thread is tapped on the semi-cylindrical surface, and the semicircle extension section of the two shells can be combined. It consists of a screw that can be installed with a metal sleeve with internal threads fixed with a steel wire rope; it also includes a cylinder with symmetrical grooves that can roll in the cylindrical cavity formed by the two shells, and the symmetrical planes of the two grooves are vertical A smooth through hole for installing the shaft is processed in the direction of the cylinder axis; it also includes a return torsion spring installed on the shaft with a straight section at the outermost end. It also includes a steel wire rope with metal sleeves with internal threads fixed at both ends, and the threads in the metal sleeves at both ends have opposite directions of rotation.

Beneficial effects of the present invention:

1. The central axis of the rotation degrees of freedom in two directions intersects at the center point of the central axis of the joint, and the force parallel to the axis of the ring is converted into the axial force of the central axis of the joint, which greatly improves the bearing capacity of the joint;

2. The internal return spring is in a pre-tightened state after being installed in the housing, and it has a reset function regardless of the hinge head turning up and down;

3. The inner thread of the metal sleeve fixed on the steel wire rope is in the opposite direction, but when two hinged joints are connected at each end, the distance between the two hinged joints can be adjusted only by turning the steel wire rope.

Description of drawings

Figure 1 Schematic diagram of the structure of a two-degree-of-freedom hinged joint with reset function

Figure 2 Appearance of the two-degree-of-freedom hinged joint with reset function

The names of the labels in the figure: 1. base, 2. shell, 3. return spring, 4. rotating shaft, 5. return torsion spring, 6. slotted cylinder, 7. metal sleeve fixed at the end of the wire rope, 8 , Wire rope, 9, shell (with countersunk hole).

specific implementation plan

Basic principle of the present invention:

1. As shown in Figure 1, when the wire rope rotates perpendicular to the paper surface, the slotted cylinder 6 rotates around the rotation axis 4, there is no relative movement between the slotted cylinder 6 and the casing 2, and a metal sleeve is installed on the extension of the casing The part of 7 forces the torsion spring 5 to twist to generate torsion. When the force driving the rotation of the steel wire rope 8 disappears, the torsion force of the torsion spring 5 forces the shell 2 to drive the slotted cylinder 6 to rotate toward the initial position to realize reset;

2. As shown in Figure 1, when the steel wire rope rotates parallel to the direction of the paper, the slotted cylinder 6 and the rotating shaft 4 are relatively stationary, and the shell 2 and the slotted cylinder 6 rotate relative to each other. Since the contact here is a cylindrical surface contact, Therefore, the carrying capacity is strong. The relative rotation between the shell 2 and the slotted cylinder 6 causes one side of the groove of the slotted cylinder to press the reset spring piece 3. Due to the symmetrical structure, the two grooves of the slotted cylinder are evenly pressed against the spring piece to deform the spring piece 3, resulting in Larger restoring force, when the force driving the wire rope to rotate disappears, the force on the spring leaf 3 drives the shell 2 to return to the initial position, completing the reset.

Both ends of the steel wire rope 8 are respectively connected with a joint, and the internal threads of the sleeves 7 at both ends rotate in the opposite direction. In or out, so as to adjust the length of the wire rope between the two joints.

Claims (4)

1. A two-degree-of-freedom articulated joint with reset function, characterized in that: each articulated joint has cylindrical grooves and spring leaf installation grooves processed in the two shells, one end of the shell has a semicircular long section, and the semi-cylindrical surface Up-tapping thread, the semicircular extensions of the two shells can be combined to form a complete screw, which can be installed with a metal casing with a steel wire rope and an internal thread. 2. The two-degree-of-freedom articulated joint with reset function according to claim 1, characterized in that: a cylinder with a smooth surface can roll in the cylindrical cavity formed by two shells, and grooves are symmetrically processed on its side , a smooth through hole for the installation shaft is machined on the symmetrical plane of the two grooves and in the direction perpendicular to the axis of the cylinder. 3. The two-degree-of-freedom articulated joint with reset function according to claim 1, characterized in that: a reset torsion spring with a straight section at the outermost end is installed on the shaft. 4. The two-degree-of-freedom articulated joint with reset function according to claim 1, characterized in that: steel wire ropes with internal threaded metal sleeves are fixed at both ends, and the threads in the metal sleeves at both ends have opposite directions of rotation.

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