CN100446941C - Parallel Mechanism with Three Translational Degrees of Freedom with Asymmetric Branches - Google Patents

Abstract

The invention discloses a three-translational degree of freedom parallel mechanism with asymmetric branch chains. It consists of a frame, a moving platform with a main shaft, and three motion branch chains arranged between the frame and the moving platform; the three motion branch chains include two telescopic active A branch chain and a parallel active branch chain arranged at the lower part of the mechanism; the two telescopic active branch chains are respectively composed of an upper Hooke hinge, a telescopic rod connected to the upper Hooke hinge, and a motor arranged at the lower part of the telescopic rod and a lower Hooke hinge arranged outside the motor; the parallel active branch chain is a planar hinge mechanism composed of two parallelogram structures connected by brackets; the connections between the three motion branch chains and the frame are all located in the mechanism below. The invention combines the active branch chain and the driven branch chain in the traditional symmetrical parallel structure into one branch chain, so that it has the functions of providing motion and providing restraint at the same time.

Description

Parallel Mechanism with Three Translational Degrees of Freedom with Asymmetric Branches

technical field

The present invention relates to an industrial robot, and more specifically, the present invention relates to a parallel machine tool mechanism with an asymmetric branch chain.

Background technique

The so-called parallel mechanism refers to a kinematic mechanism with a multi-loop closed kinematic chain with 2 to 6 degrees of freedom. Compared with the series mechanism, it has the characteristics of large stiffness/mass ratio and easy modular design, so it has been widely used in industrial robots, CNC machine tools, motion simulators, medical robots, and precision in microelectronics manufacturing. Positioning device and many other aspects.

The existing space parallel mechanisms with few degrees of freedom are generally symmetrical, which usually require the active branch itself or a driven branch to provide certain constraints on the degrees of freedom of the moving platform. For example, the Delta mechanism in Switzerland belongs to a symmetrical structure, and the rotational freedom of its moving platform is limited by the parallelogram structure of its branches, so that the moving platform can only do three-dimensional translation. Another example is the Tricept series five-degree-of-freedom hybrid manipulator produced by Neos Robotics in Sweden. Its parallel mechanism consists of three symmetrically distributed active telescopic rods and a telescopic driven rod to determine the rotational position of the moving platform. The above-mentioned driven rod rotates around its own axis and at the same time around two axes orthogonal to the axis, thereby realizing the movement of the reference point of the moving platform in three degrees of freedom in the spherical coordinate system. Another example is the SMK three-translational degree-of-freedom parallel machine tool produced by the German Heckert company. The spatial position of the moving platform is determined by three symmetrically distributed telescopic rods, and the driven branch chain composed of a parallelogram mechanism is limited to be orthogonal to the axis of the moving platform. rotation of the two axes.

Although the above-mentioned parallel mechanism with symmetrical driven branches has high rigidity, since the driving branches and driven branches are separated from each other, the mechanical structure is relatively complicated, the number of kinematic pairs is large, and the occupied space is relatively large.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and provide a three-translational degrees of freedom parallel mechanism with asymmetric branch chains, which has a simple and compact structure, takes up little space, and has a small number of kinematic pairs.

The three-translational degrees of freedom parallel mechanism with asymmetric branch chains of the present invention is composed of a frame, a moving platform provided with a main shaft, and three moving branch chains arranged between the frame and the moving platform; the three The motion branch chain includes two telescopic active branch chains arranged on both sides of the mechanism and a parallel active branch chain arranged at the lower part of the mechanism; the two telescopic active branch chains are respectively composed of the upper Hooke hinge and the upper The telescopic rod connected by the Hooke hinge, the motor arranged at the lower part of the telescopic rod and the lower Hooke hinge arranged outside the motor, the upper ends of the two telescopic active branch chains are respectively arranged on the bottom of the moving platform through the upper Hooke hinge. On the two sides, the lower ends of the two telescopic active branch chains are respectively connected to the frame through the lower Hooke hinge; the parallel active branch chains are planar hinge mechanisms composed of two parallelogram structures connected by brackets, and the The first parallelogram structure consists of a bracket, an active arm and a secondary active arm respectively arranged at the upper and lower ends of the bracket, and a rotating shaft arranged between the active arm and the secondary active arm. One arm of the parallelogram is provided There is a driving motor; the second parallelogram structure is composed of a bracket, a moving platform, a driven arm and a secondary driven arm respectively arranged at the front end and rear end of the moving platform and connected to the bracket.

A balance device consisting of an auxiliary support rod connected to a balance spring is arranged between the moving platform and the active arm, one end of the balance device is hinged to the rear end of the moving platform, and the other end is connected to the active arm. The rear end of the arm is hinged; the balance spring is any one of mechanical tension and compression springs, air springs or hydraulic springs.

The joints between the three motion branch chains and the frame are all located below the mechanism; the components of the plane hinge mechanism are connected by rotating pairs; each arm of the plane hinge mechanism adopts a frame structure.

The invention combines the active branch chain and the driven branch chain in the traditional symmetrical parallel structure with driven branch chains into one branch chain, which not only makes it have the functions of providing movement and providing restraint, but also makes it compact in structure, The number of motion pairs is small and the space occupied is small.

Description of drawings

Fig. 1 is one of structural representation of the present invention;

Fig. 2 is the second structural diagram of the present invention.

Marks in the figure: bracket 1, motor 2, lower hook hinge 3, driven arm 4, telescopic rod 5, main shaft 6, moving platform 7, upper hook hinge 8, main arm 9, motor 10, auxiliary main arm 11, Balance spring 12, auxiliary support rod 13, auxiliary follower arm 14, frame 15, rotating shaft 16.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Figure 1 and Figure 2 are structural schematic diagrams of the present invention at two different angles. As can be seen from the figure, the present invention consists of a frame 15, a moving platform 7, and three motion branch chains arranged between the frame 15 and the moving platform 7; chain and a parallel active branch chain, the two telescopic active branch chains are respectively arranged on both sides of the mechanism, and the one parallel active branch chain is arranged at the lower part of the mechanism; the two telescopic active branch chains have the same composition, both Yes: the upper end of the telescopic rod 5 is set on the side of the moving platform 7 through the upper Hooke hinge 8, and a rotating pair is formed between the upper Hooke hinge 8 and the telescopic rod 5, and the lower end of the telescopic rod 5 is equipped with a motor 2 , the motor 2 is arranged in the lower Hooke hinge 3 through the collinear shafts on both sides, and the lower Hooke hinge 3 is connected to the frame 15, so that the motor 2 can be freely rotated in two directions. Swing, and control the telescopic length of the telescopic rod 5 between the frame 15 and the moving platform 7; the parallel active branch chain is a plane hinge mechanism, which is composed of two parallelogram structures connected by the bracket 1; The first parallelogram structure is composed of a bracket 1, a main arm 9 and a secondary main arm 11 respectively arranged on the upper and lower ends of the support 1, and a rotating shaft 16 arranged between the main arm 9 and the secondary main arm 11; The second parallelogram structure described is composed of a support 1, a moving platform 7, a driven arm 4 and a secondary driven arm 14 that are respectively arranged on the front end and the rear end of the moving platform 7 and are connected to the support 1; in order to overcome the moving platform 7 And the gravity of other parts, reduce the static moment of motor, be provided with between described moving platform 7 and described active arm 9 by the balance device that is connected balance spring 12 to form by auxiliary support bar 13, to play against moving platform 7 support role. The balance spring in the balance device can be a mechanical tension-compression spring, or any one of an air spring or a hydraulic spring.

In the parallel active branch chain, the rotating shaft 16 is connected to the frame 15 through a rotating hinge, so that the parallel active branching chain can freely swing around the rotating shaft of the rotating hinge. This structural layout can make the rotation around the axis of the movable platform 7 a function of its position, and at the same time limit the two rotational degrees of freedom orthogonal to the axis, thereby realizing the three-dimensional translation of the movable platform 7 in space. The main components in the parallel active branch chain adopt a frame structure to provide sufficient static and dynamic rigidity. In the parallelogram formed by the support 1, the active arm 9, the auxiliary active arm 11 and the rotating shaft 16, an arm (the active arm 9) is provided with a driving motor 10, and when the driving motor 10 rotates, it can drive the active arm 9 around the rotating shaft 16 turns. Because the active arm 9 is connected to the driven arm 4, thereby driving the moving platform 7 to move; and because the two parallelograms are connected by the bracket 1 to form a parallel mechanism that provides both movement and constraint functions, the setting is limited. The degree of freedom of rotation of the main shaft 6 on the moving platform 7; also because each arm (master arm 9, secondary master arm 11, slave arm 4 and slave slave arm 14) of this parallel active branch has adopted a frame structure, so that It can absorb the vibration generated when the machine tool is working, and can improve the torsional rigidity of the machine tool.

The three-translational degrees of freedom parallel mechanism with asymmetric branch chains of the present invention integrates the structure of a driving branch chain and a driven branch chain in a traditional symmetrical parallel structure, which not only simplifies its structure, but also makes it have In order to provide the functions of motion and restriction; in addition, the structural setting of the asymmetric branch chain of the present invention can make the connection positions of the three motion branch chains and the frame 15 all be below the mechanism, and this arrangement reduces the frame. The height saves the occupied space of the machine tool structure.

The above descriptions of the present invention and its implementations are schematic, not restrictive, and what is shown in the drawings is only one of the implementations of the present invention, and the actual structure is not limited thereto. Therefore, if a person of ordinary skill in the art is inspired by it and makes other embodiments without departing from the inventive concept of the present invention, it shall fall within the protection scope of the present invention.

Claims (6)

1. three-translational freedom degree parallel connection mechanism with asymmetric side chain is by frame, be provided with the moving platform of main shaft and three movement branched chain being arranged between described frame and the moving platform constitute; It is characterized in that: described three movement branched chain comprise two the flexible active branched chain and a parallel active branched chain that is arranged on the mechanism bottom that are separately positioned on the mechanism both sides; Described two flexible active branched chain are respectively by last Hooke's hinge, constitute with the following Hooke's hinge of describedly going up expansion link that Hooke's hinge is connected, be arranged on the motor of expansion link bottom and be arranged on the motor outside, the upper end of described two flexible active branched chain is arranged on two sides of described moving platform respectively by last Hooke's hinge, the lower end of described two flexible active branched chain is passed through Hooke's hinge connection frame down respectively; Described parallel active branched chain is the plane linkwork of forming by two parallelogram sturcutres that support connects, described first parallelogram sturcutre by support, the master arm that is separately positioned on described support top and bottom and secondary master arm and be arranged on described master arm and secondary master arm between rotating shaft constitute, an arm of this parallelogram is provided with drive motors; Described second parallelogram sturcutre is made of support, moving platform, the slave arm and the secondary slave arm that are separately positioned on described moving platform front-end and back-end and connect support.

2. the three-translational freedom degree parallel connection mechanism with asymmetric side chain according to claim 1, it is characterized in that: be provided with by auxiliary support bar between described moving platform and the described master arm and be connected the bascule that balancing spring constitutes, one end of described bascule and the rear end of described moving platform are hinged, and the rear end of its other end and described master arm is hinged.

3. the three-translational freedom degree parallel connection mechanism with asymmetric side chain according to claim 2 is characterized in that: described balancing spring is any in mechanical type drawing-pressing spring, air spring or the hydraulic spring grease cup.

4. the three-translational freedom degree parallel connection mechanism with asymmetric side chain according to claim 1 is characterized in that: the junction of described three movement branched chain and frame all is positioned at the mechanism below.

5. the three-translational freedom degree parallel connection mechanism with asymmetric side chain according to claim 1 is characterized in that: be revolute pair between each member of described plane linkwork and connect.

6. the three-translational freedom degree parallel connection mechanism with asymmetric side chain according to claim 1 is characterized in that: each arm of described plane linkwork all adopts frame structure.

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